Method for treating a pulmonary hypertension condition

ABSTRACT

A method for treating a pulmonary hypertension condition such as pulmonary arterial hypertension (PAH) in a subject comprises administering to the subject a therapeutically effective amount of ambrisentan, wherein, at baseline, time from first diagnosis of the condition in the subject is not greater than about 2 years.

This application claims the benefit of U.S. provisional application Ser.No. 60/869,667, filed Dec. 12, 2006, incorporated in its entirety hereinby reference.

FIELD OF THE INVENTION

The present invention relates to methods useful for treating a subjecthaving a pulmonary hypertension condition, and for improving clinicaloutcome in such a subject.

BACKGROUND OF THE INVENTION

Pulmonary hypertension (PH) has been previously classified as primary(idiopathic) or secondary. Recently, the World Health Organization (WHO)has classified pulmonary hypertension into five groups:

-   -   Group 1: pulmonary arterial hypertension (PAH);    -   Group 2: PH with left heart disease;    -   Group 3: PH with lung disease and/or hypoxemia;    -   Group 4: PH due to chronic thrombotic and/or embolic disease;        and    -   Group 5: miscellaneous conditions (e.g., sarcoidosis,        histiocytosis X, lymphangiomatosis and compression of pulmonary        vessels).

See, for example, Rubin (2004) Chest 126:7-10.

Pulmonary arterial hypertension (PAH) is a serious, progressive andlife-threatening disease of the pulmonary vasculature, characterized byprofound vasoconstriction and an abnormal proliferation of smooth musclecells in the walls of the pulmonary arteries. Severe constriction of theblood vessels in the lungs leads to very high pulmonary arterialpressures. These high pressures make it difficult for the heart to pumpblood through the lungs to be oxygenated. Patients with PAH suffer fromextreme shortness of breath as the heart struggles to pump against thesehigh pressures. Patients with PAH typically develop significantincreases in pulmonary vascular resistance (PVR) and sustainedelevations in pulmonary artery pressure (PAP), which ultimately lead toright ventricular failure and death. Patients diagnosed with PAH have apoor prognosis and equally compromised quality of life, with a mean lifeexpectancy of 2 to 5 years from the time of diagnosis if untreated.

Endothelin-1 (ET-1) is the primary member of a family of potentvasoconstrictor peptides, which are known to play an essential role inmammalian cardiovascular physiology. ET-1 is synthesized de novo andreleased from endothelial cells in response to a variety of factors,including angiotensin II, catecholamines, cytokines, hypoxia and shearstress. Two receptor subtypes, endothelin receptor type A (ET_(A)) andendothelin receptor type B (ET_(B)), mediate the effects of ET-1. Inhumans, the ET_(A) receptor is preferentially expressed in vascularsmooth muscle cells and is primarily responsible for thevasoconstrictive effects of ET-1. In contrast, ET_(B) receptors arefound mainly in the vascular endothelium, and their activation resultsin vasodilatation via production of nitric oxide and prostacyclin. TheET_(B) receptor is also involved in regulation of circulatingconcentrations of ET-1, through effects on endothelin converting enzyme(ECE-1) expression, and the synthesis and reuptake of ET-1 byendothelial cells.

Ambrisentan is a non-sulfonamide, propanoic acid-class endothelinreceptor antagonist (ERA) with high affinity (˜12 pM) for the ET_(A)receptor. Bosentan, a non-selective, sulfonamide-class ERA, is approvedfor treatment of PAH in patients with WHO functional class III or IVsymptoms. Sitaxsentan is another sulfonamide-class ERA that is selectivefor the ET_(A) receptor. Sitaxsentan is currently under review formarket authorization as a PAH therapeutic.

Myogen, Inc. News Release, Dec. 4, 2003(http://www.pmewswire.com/cgi-bin/stories.pl?ACCT=104&STORY=/www/story/12-04-2003/0002069898&EDATE=)announced completion of a Phase II trial of ambrisentan in PAH andinitiation of Phase III trials. The release stated that the Phase IIItrials would evaluate 2.5 mg, 5.0 mg and 10.0 mg oral dosages ofambrisentan administered once a day, and would have as a primaryefficacy endpoint exercise capacity, which measures the change frombaseline in 6-minute walk distance (6MWD) compared to placebo, andsecondary endpoints including Borg dyspnea index (BDI), WHO functionalclass and a quality of life assessment.

Myogen, Inc. News Release, Jan. 8, 2004(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=759080&highlight=)announced patient enrollment in phase III clinical trials of ambrisentanfor treatment of PAH. According to the news release, phase II trials haddemonstrated a statistically significant and clinically meaningfulincrease in the primary efficacy endpoint (exercise capacity measured by6MWD) in all four ambrisentan dose groups tested.

Myogen, Inc. News Release, Feb. 16, 2004(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=759478&highlight=)announced upcoming presentation of detailed results of the phase IIstudy of ambrisentan in PAH, at the American Thoracic Society (ATS) 2004International Conference. (Rubin (2004) “Ambrisentan Improves ExerciseCapacity and Clinical Measures in Pulmonary Arterial Hypertension”, ATSMay 21-26, 2004.)

Myogen, Inc. News Release, May 24, 2004(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=759469&highlight=)reported improvements in 6MWD, BDI and WHO functional classificationseen in the Phase II study. Additionally, the news release mentionedsuitability of ambrisentan for once-a-day dosing.

Myogen, Inc. News Release, Feb. 10, 2005(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=759971&highlight=)announced that two abstracts describing effects of ambrisentan inpatients with PAH were selected for presentation at ATS 2005 in SanDiego. (Galié (2005) “Ambrisentan Long-Term Safety and Efficacy inPulmonary Arterial Hypertension 1-Year Follow-Up”, ATS May 23, 2005;Frost (2005) “Ambrisentan Improves 6MWD Comparably for WHO Class II andIII PAH Patients,” ATS May 22, 2005.) It was stated that one-year datademonstrated that ambrisentan produced a significant and durable benefiton exercise capacity and other clinical measures of PAH and that WHOClass II and III PAH patients have significant and comparableimprovement in exercise capacity, suggesting that the effects ofambrisentan are not limited by the “ceiling effect” in patients withless severe PAH symptoms.

Myogen, Inc. News Release, May 19, 2005(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=759658&highlight=)reported initiation of a clinical trial to evaluate ambrisentan inpatients with PAH who have previously discontinued bosentan orsitaxsentan therapy due to liver function test (LFT) abnormalities,specifically elevated serum aminotransferase concentrations.

Myogen, Inc. News Release, May 23, 2005(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=759656&highlight=)reported further data presented by Galié (2005) ATS 2005, cited above,which were stated to show improvements in a 6-minute walking test (6MWT)accompanied with improved levels of dyspnea (breathlessness) for WHOClass II and III patients. The release reported a one-year survival rateof 92% for patients with idiopathic PAH as compared to an NIH registrypredicted survival of 74%.

Myogen, Inc. News Release, Jul. 21, 2005(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=759650&highlight=)announced completion of enrollment of 187 patients in ARIES-2, one ofthe two Phase III clinical trials of ambrisentan in patients with PAH.The news release reported that ARIES-1 evaluates doses of 5.0 mg and10.0 mg of ambrisentan administered orally once daily, while ARIES-2provides 2.5 mg and 5.0 mg dosages. The release stated that the resultsof the Phase II clinical trial of ambrisentan in patients with PAHdemonstrated significant improvements in 6MWD, BDI and WHO functionalclass, durable efficacy with long-term use and a possible survivalbenefit, comparable efficacy in WHO Functional Class 2 and Class 3patients, selectivity for the endothelin type-A receptor, doseflexibility, true once-daily dosing, no drug interactions (no p450induction or inhibition), and low incidence and severity of potentialliver toxicity that does not appear to be dose related.

Myogen, Inc. News Release, Nov. 10, 2005(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=781654&highlight=)announced the expectation that ARIES-2 results would be reported inDecember of that year.

Rubin et al. (2005) Future Cardiol. 1(4):1-8 reported improvement of themean 6MWD for all patients after 12 weeks of ambrisentan treatment, witha mean increase from baseline of 36 meters. The authors reported thatsimilar improvements in 6MWD were observed for patients with WHOFunctional Class II and III symptoms, indicating that the effects ofambrisentan may not be limited by a “ceiling effect” in less advancedPAH patients, as has been reported for sitaxsentan. Additionally, theauthors reported that clinically meaningful improvements were also seenin BDI and WHO functional class.

Galié et al. (2005) J. Am. Coll. Cardiol. 46(3):529-535 reported resultsof a randomized dose-ranging study examining efficacy and safety ofambrisentan in patients with PAH. The authors reported an increase inexercise capacity in patients with idiopathic PAH as well as in patientswith PAH due to other etiologies and for patients in WHO FunctionalClass II as well as those in WHO Functional Class III.

PAH afflicts approximately 200,000 patients worldwide. Improved drugtherapies to treat pulmonary hypertensive disorders such as PAH areneeded in the art. Further, methods for enhancing the clinical outcomefor patients having pulmonary hypertension conditions would be highlydesirable.

SUMMARY OF THE INVENTION

There is now provided a method for treating a pulmonary hypertensioncondition in a subject, comprising administering a therapeuticallyeffective amount of ambrisentan to the subject, wherein, at baseline,time from first diagnosis of the condition in the subject is not greaterthan about 2 years.

There is further provided a method for providing an improved prognosisfor a subject having a pulmonary hypertension condition, comprisingadministering to the subject ambrisentan at a dose and frequency and fora treatment period effective to provide (a) a reduction of at leastabout 25% in probability of a clinical worsening event during thetreatment period, and/or (b) a reduction from baseline of at least about15% in serum brain natriuretic peptide (BNP) concentration; wherein, atbaseline, time from first diagnosis of the condition in the subject isnot greater than about 2 years.

There is still further provided a method for prolonging life of asubject having a pulmonary hypertension condition, comprisingadministering to the subject ambrisentan at a dose and frequency and fora treatment period effective to increase life expectancy, from a time ofinitiation of treatment, by at least about 30 days; wherein, atbaseline, time from first diagnosis of the condition in the subject isnot greater than about 2 years.

There is still further provided a method for extending time to clinicalworsening in a subject having PAH, comprising administering to thesubject ambrisentan at a dose and frequency and for a treatment periodeffective to decrease the probability of a clinical worsening event byat least about 25%; wherein, at baseline, time from first diagnosis ofthe condition in the subject is not greater than about 2 years.

There is still further provided a method for treating a pulmonaryhypertension condition in a reproductively active male subject, themethod comprising administering a therapeutically effective amount ofambrisentan to the subject, wherein fertility of the subject is notsubstantially compromised.

Any of the above methods is applicable to any pulmonary hypertensioncondition recognized in the WHO classification, including pulmonaryarterial hypertension (PAH) as classified in WHO Group 1.

There is still further provided a method for treating PAH in a subject,comprising administering a therapeutically effective amount ofambrisentan to the subject, wherein the PAH is associated with one ormore of (a) a congenital heart defect such as a systemic-to-pulmonaryshunt or Eisenmenger's syndrome, (b) portal hypertension, (c) use of adrug or toxin other than an anorexigen, (d) thyroid disorder, (e)glycogen storage disease, (f) Gaucher disease, (g) hereditaryhemorrhagic telangiectasia, (h) hemoglobinopathy, (i) myeloproliferativedisorder, (j) splenectomy, (k) pulmonary veno-occlusive disease and/or(l) pulmonary capillary hemangiomatosis.

There is still further provided a method for treating a pulmonaryhypertension condition classified in WHO Groups 2-5 in a subject,comprising administering a therapeutically effective amount ofambrisentan to the subject.

Other embodiments, including particular aspects of the embodimentssummarized above, will be evident from the detailed description thatfollows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides Kaplan-Meier curves for time to clinical worsening ofPAH from the study described in Example 1.

FIG. 2 provides Kaplan-Meier curves for time to clinical worsening ofPAH from the study described in Example 2.

DETAILED DESCRIPTION

The present invention is based in part on a finding, inplacebo-controlled clinical trials, that ambrisentan is effective fortreatment of a pulmonary hypertension condition, more specificallypulmonary arterial hypertension (PAH), in subjects wherein the conditionis relatively recently diagnosed. In the above-referenced presentationby Rubin (2004) at ATS 2004, subjects treated with ambrisentan werereportedly characterized at baseline by a mean time since diagnosis of3.2±3.8 years. In the absence of placebo control, it is not possible todetermine how these subjects might have fared had they not been giventhe benefit of ambrisentan therapy.

It is noted, however, that a prediction based on the National Institutesfor Health (NIH) registry is that only 74% of patients having adiagnosis of idiopathic PAH survive for 1 year (above-referencedpresentation by Galié (2005) at ATS 2005). A cohort of patients thathave survived with the disease for a longer period of time may not berepresentative of patients with more recent diagnosis, as that cohortmay be inadvertently biased in favor of individuals better able tosurvive for a prolonged period.

The sooner treatment can begin after diagnosis, the better. Accordingly,in a first embodiment of the invention, a method for treating apulmonary hypertension condition in a subject comprises administering atherapeutically effective amount of ambrisentan to the subject, wherein,at baseline, time from first diagnosis of the condition in the subjectis not greater than about 2 years, for example not greater than about1.5 years, not greater than about 1 year, not greater than about 0.75year or not greater than about 0.5 year. In one aspect of the firstembodiment, administration of ambrisentan can begin substantiallyimmediately, for example within about one month or within about oneweek, upon diagnosis.

This method does not in any way negate ambrisentan therapy for subjectshaving a longer history of the condition. However, it recognizes thatearly intervention is advantageous. Benefits of the method to subjectshaving recent diagnosis (and poor prognosis without early interventionas exhibited, for example, in the NIH registry mentioned above) have nowbeen quantified for the first time. Illustratively, in theplacebo-controlled study described in Example 1 below, the median numberof years for which PAH was present at baseline was 0.38 for subjectsreceiving placebo, 0.43 years for subjects receiving 2.5 mg ambrisentandaily, and 0.26 years for subjects receiving 5 mg ambrisentan daily. Inthe placebo-controlled study described in Example 2 below, the mediannumber of years for which PAH was present at baseline was 0.54 forsubjects receiving placebo, 0.33 years for subjects receiving 5 mgambrisentan daily, and 0.60 years for subjects receiving 10 mgambrisentan daily.

Except where otherwise indicated herein, the term “baseline” hereinmeans a time immediately prior to initiation of treatment withambrisentan.

The term “diagnosis” herein means recognition by a physician orclinician of a pulmonary hypertension condition, for example PAH, in thesubject, by any means whether or not such diagnosis is confirmed byhemodynamic evaluation. In one aspect of the first embodiment, diagnosisis confirmed hemodynamically, for example in the case of PAH by presenceof one or more, more typically two or all three of the following:

-   -   (a) mean pulmonary arterial pressure (PAP) not less than about        25 mmHg at rest or not less than about 30 mmHg while exercising;    -   (b) pulmonary vascular resistance (PVR) not less than about 3        mmHg/liter/minute;    -   (c) pulmonary capillary wedge pressure (PCWP) or left ventricle        end diastolic pressure (LVEDP) not greater than about 15 mmHg.        The pulmonary hypertension condition diagnosed, and treated by        the method of the first embodiment, can comprise any one or more        of the conditions recognized according to the World Health        Organization (WHO) or Venice (2003) classification (see, for        example, Rubin (2004) Chest 126:7-10):    -   Group 1: Pulmonary arterial hypertension (PAH)        -   1.1 idiopathic PAH        -   1.2 familial PAH        -   1.3 PAH associated with:            -   1.3.1 collagen vascular disease            -   1.3.2 congenital systemic-to-pulmonary shunts (including                Eisenmenger's syndrome)            -   1.3.3 portal hypertension            -   1.3.4 HIV infection            -   1.3.5 drugs and toxins            -   1.3.6 other (thyroid disorders, glycogen storage                disease, Gaucher disease, hereditary hemorrhagic                telangiectasia, hemoglobinopathies, myeloproliferative                disorders, splenectomy)        -   1.4 PAH associated with significant venous or capillary            involvement            -   1.4.1 pulmonary veno-occlusive disease (PVOD)            -   1.4.2 pulmonary capillary hemangiomatosis (PCH)        -   1.5 persistent pulmonary hypertension of the newborn    -   Group 2: Pulmonary hypertension with left heart disease        -   2.1 left-sided atrial or ventricular heart disease        -   2.2 left-sided valvular heart disease    -   Group 3: Pulmonary hypertension associated with lung diseases        and/or hypoxemia        -   3.1 chronic obstructive pulmonary disease (COPD)        -   3.2 interstitial lung disease        -   3.3 sleep-disordered breathing        -   3.4 alveolar hypoventilation disorders        -   3.5 chronic exposure to high altitude        -   3.6 developmental abnormalities    -   Group 4: Pulmonary hypertension due to chronic thrombotic and/or        embolic disease        -   4.1 thromboembolic obstruction of proximal pulmonary            arteries        -   4.2 thromboembolic obstruction of distal pulmonary arteries        -   4.3 non-thrombotic pulmonary embolism (tumor, parasites,            foreign material)    -   Group 5: Miscellaneous (sarcoidosis, histiocytosis X,        lymphangiomatosis, compression of pulmonary vessels (adenopathy,        tumor, fibrosing mediastinitis))

In one aspect, the pulmonary hypertension condition comprises PAH (WHOGroup 1), for example idiopathic PAH, familial PAH or PAH associatedwith another disease or condition.

Pulmonary hypertension at baseline can be mild, moderate or severe, asmeasured for example by WHO functional class, which is a measure ofdisease severity in patients with pulmonary hypertension. The WHOfunctional classification is an adaptation of the New York HeartAssociation (NYHA) system and is routinely used to qualitatively assessactivity tolerance, for example in monitoring disease progression andresponse to treatment (Rubin (2004) Chest 126:7-10). Four functionalclasses are recognized in the WHO system:

-   -   Class I: pulmonary hypertension without resulting limitation of        physical activity; ordinary physical activity does not cause        undue dyspnea or fatigue, chest pain or near syncope;    -   Class II: pulmonary hypertension resulting in slight limitation        of physical activity; patient comfortable at rest; ordinary        physical activity causes undue dyspnea or fatigue, chest pain or        near syncope;    -   Class III: pulmonary hypertension resulting in marked limitation        of physical activity; patient comfortable at rest; less than        ordinary activity causes undue dyspnea or fatigue, chest pain or        near syncope;    -   Class IV: pulmonary hypertension resulting in inability to carry        out any physical activity without symptoms; patient manifests        signs of right-heart failure; dyspnea and/or fatigue may be        present even at rest; discomfort is increased by any physical        activity.

In one aspect of the first embodiment, the subject at baseline exhibitspulmonary hypertension (e.g., PAH) of at least WHO Class II, for exampleWHO Class II or Class III.

In another aspect, the subject at baseline exhibits mean PAP at rest ofat least about 30 mmHg, for example at least about 35, at least about40, at least about 45 or at least about 50 mmHg.

The term “treatment” herein encompasses one or more of the following:

-   -   (a) adjustment of one or more hemodynamic parameters towards a        more normal level, for example lowering mean PAP or PVR, or        raising PCWP or LVEDP, versus baseline;    -   (b) improvement of pulmonary function versus baseline, for        example increasing exercise capacity, illustratively as measured        in a test of 6-minute walking distance (6MWD), or lowering Borg        dyspnea index (BDI);    -   (c) improvement of one or more quality of life parameters versus        baseline, for example an increase in score on at least one of        the SF-36® health survey functional scales;    -   (d) general improvement versus baseline in the severity of the        condition, for example by movement to a lower WHO functional        class;    -   (e) improvement of clinical outcome following a period of        treatment, versus expectation in absence of treatment (e.g., in        a clinical trial setting, as measured by comparison with        placebo), including improved prognosis, extending time to or        lowering probability of clinical worsening, extending quality of        life (e.g., delaying progression to a higher WHO functional        class or slowing decline in one or more quality of life        parameters such as SF-36® health survey parameters), and/or        increasing longevity; and/or    -   (f) adjustment towards a more normal level of one or more        molecular markers that can be predictive of clinical outcome        (e.g., plasma concentrations of endothelin-1 (ET-1), cardiac        troponin T (cTnT) or B-type natriuretic peptide (BNP)).

Except where otherwise indicated herein, a “therapeutically effectiveamount” of ambrisentan is an amount (typically a daily amountadministered over the course of a period of treatment) sufficient toprovide any one or more of the effects mentioned above. Preferably theamount administered does not exceed an amount causing an unacceptabledegree of adverse side effects.

What constitutes a therapeutically effective amount can vary dependingon the particular pulmonary hypertension condition to be treated, theseverity of the condition, body weight and other parameters of theindividual subject, and can be readily established without undueexperimentation by the physician or clinician based on the disclosureherein. Typically, a therapeutically effective amount will be found inthe range of about 1 to about 25 mg/day, for example about 2 to about 15mg/day, about 2.5 to about 10 mg/day, or about 2.5, about 3, about 3.5,about 4, about 4.5, about 5, about 6, about 7, about 8, about 9 or about10 mg/day.

Such an amount can be administered each day, for example in individualdoses administered once, twice, or three or more times a day. However,dosages stated herein on a per day basis should not be construed torequire administration of the daily dose each and every day. Forexample, if the ambrisentan is provided in a suitably slow-release form,two or more daily dosage amounts can be administered at a lowerfrequency, e.g., as a depot every second day to once a month or evenlonger. Most typically and conveniently for the patient, ambrisentan isadministered once a day, for example in the morning.

The ambrisentan can be administered for an extended treatment period.Typically, the longer the treatment continues, the greater and morelasting will be the benefits. Illustratively, the treatment period canbe at least about one month, for example at least about 3 months, atleast about 6 months or at least about 1 year. In some cases,administration can continue for substantially the remainder of the lifeof the subject.

In this and other embodiments, ambrisentan can be administered by anysuitable route including oral, rectal, intranasal, intrapulmonary (e.g.,by inhalation) or parenteral (e.g., intradermal, transdermal,subcutaneous, intramuscular or intravenous) routes. Oral administrationis most convenient for the majority of subjects and can occurindependently of meal times, i.e., with or without food.

The ambrisentan can be administered in monotherapy or in combinationtherapy as described in greater detail hereinbelow.

In various aspects of the first embodiment, the subject experiences,during or following the treatment period, at least one of

-   -   (a) adjustment of one or more hemodynamic parameters indicative        of the pulmonary hypertension condition towards a more normal        level versus baseline;    -   (b) increase in exercise capacity versus baseline;    -   (c) lowering of BDI versus baseline;    -   (d) improvement of one or more quality of life parameters versus        baseline; and/or    -   (e) movement to a lower WHO functional class.

Any suitable measure of exercise capacity can be used; a particularlysuitable measure is obtained in a 6-minute walk test (6MWT), whichmeasures how far the subject can walk in 6 minutes, i.e., the 6-minutewalk distance (6MWD).

The Borg dyspnea index (BDI) is a numerical scale for assessingperceived dyspnea (breathing discomfort). It measures the degree ofbreathlessness after completion of the 6 minute walk test (6MWT), wherea BDI of 0 indicates no breathlessness and 10 indicates maximumbreathlessness.

In various aspects of the first embodiment, the ambrisentan can beadministered in an amount effective to adjust one or more hemodynamicparameters indicative of the pulmonary hypertension condition towards amore normal level. In one such aspect, mean PAP is lowered, for exampleby at least about 3 mmHg, or at least about 5 mmHg, versus baseline. Inanother such aspect, PVR is lowered. In yet another such aspect, PCWP orLVEDP is raised.

In various aspects of the first embodiment, the ambrisentan can beadministered in an amount effective to improve pulmonary function versusbaseline. Any measure of pulmonary function can be used; illustratively6MWD is increased or BDI is lowered.

In one such aspect, 6MWD is increased from baseline by at least about 10m, for example at least about 20 m or at least about 30 m. In manyinstances, the method of the present embodiment will be found effectiveto increase 6MWD by as much as 50 m or even more.

In another such aspect, BDI, illustratively as measured following a6MWT, is lowered from baseline by at least about 0.5 index points. Inmany instances, the method of the present embodiment will be foundeffective to lower BDI by as much as 1 full index point or even more.

The SF-36® health survey provides a self-reporting, multi-item scalemeasuring eight health parameters: physical functioning, rolelimitations due to physical health problems, bodily pain, generalhealth, vitality (energy and fatigue), social functioning, rolelimitations due to emotional problems, and mental health (psychologicaldistress and psychological well-being). The survey also provides aphysical component summary and a mental component summary. For furtherdetail see, for example, Ware: SF-36® Health Survey Update,http://www.sf-36.org/tools/sf36.shtml.

In various aspects of the first embodiment, the ambrisentan can beadministered in an amount effective to improve quality of life of thesubject, illustratively as measured by one or more of the healthparameters recorded in an SF-36® survey. For example, an improvementversus baseline is obtained in at least one of the SF-36 physical healthrelated parameters (physical health, role-physical, bodily pain and/orgeneral health) and/or in at least one of the SF-36 mental healthrelated parameters (vitality, social functioning, role-emotional and/ormental health). Such an improvement can take the form of an increase ofat least 1, for example at least 2 or at least 3 points, on the scalefor any one or more parameters.

The ambrisentan can be administered in monotherapy or in combinationtherapy with one or more additional drugs, for example, as described ingreater detail hereinbelow.

In a second embodiment of the invention, a method is provided forimproving the prognosis for a subject having a pulmonary hypertensioncondition. The method of this embodiment comprises administering to thesubject ambrisentan at a dose and frequency and for a treatment periodeffective to provide (a) a reduction in probability of a clinicalworsening event during the treatment period, and/or (b) a reduction frombaseline in serum brain natriuretic peptide (BNP) concentration,wherein, at baseline, time from first diagnosis of the condition in thesubject is not greater than about 2 years.

Time from first diagnosis, in various aspects of the second embodiment,can be, for example, not greater than about 1.5 years, not greater thanabout 1 year, not greater than about 0.75 year or not greater than about0.5 year. In one aspect of the second embodiment, administration ofambrisentan can begin substantially immediately, for example, withinabout one month or within about one week, upon diagnosis.

In the method of the second embodiment, the ambrisentan is administeredat a dose and frequency and for a period of treatment sufficient toprovide one or both of the effects mentioned above. Preferably the doseadministered does not exceed an amount causing an unacceptable degree ofadverse side effects. The dose administered can vary depending on theparticular pulmonary hypertension condition to be treated, the severityof the condition, body weight and other parameters of the individualsubject, and can be readily established without undue experimentation bythe physician or clinician based on the disclosure herein.

Typically, a suitable daily dose will be found in the range of about 1to about 25 mg/day, for example about 2 to about 15 mg/day, about 2.5 toabout 10 mg/day, or about 2.5, about 3, about 3.5, about 4, about 4.5,about 5, about 6, about 7, about 8, about 9 or about 10 mg/day. Such anamount can be administered each day, for example in individual dosesadministered once, twice, or three or more times a day. However, dosagesstated herein on a per day basis should not be construed to requireadministration of the daily dose each and every day. For example, if theambrisentan is provided in a suitably slow-release form, two or moredaily dosage amounts can be administered at a lower frequency, e.g., asa depot every second day to once a month or even longer. Most typicallyand conveniently for the patient, ambrisentan is administered once aday, for example in the morning.

In the method of the second embodiment, the treatment period is longenough for the stated effect to be produced. Typically, the longer thetreatment continues, the greater and more lasting will be the benefits.Illustratively, the treatment period can be at least about one month,for example at least about 3 months, at least about 6 months or at leastabout 1 year. In some cases, administration can continue forsubstantially the remainder of the life of the subject.

In various aspects of the second embodiment, the ambrisentan can beadministered in monotherapy or in combination therapy as described ingreater detail hereinbelow.

In a particular aspect of the second embodiment, the method is effectiveto provide a reduction of at least about 25%, for example at least about50%, at least about 75% or at least about 80%, in probability of aclinical worsening event during the treatment period.

Clinical worsening event (CWEs) include death, lung transplantation,hospitalization for the pulmonary hypertension condition, atrialseptostomy, initiation of additional pulmonary hypertension therapy oran aggregate thereof. Therefore, the present embodiment provides amethod effective to provide a reduction of at least about 25%, forexample at least about 50%, at least about 75% or at least about 80%, inprobability of death, lung transplantation, hospitalization forpulmonary arterial hypertension, atrial septostomy and/or initiation ofadditional pulmonary hypertension therapy during the treatment period.

Time to clinical worsening of the pulmonary hypertension condition isdefined as the time from initiation of a ambrisentan treatment regime tothe first occurrence of a CWE.

In another particular aspect of the second embodiment, the method iseffective to provide a reduction from baseline of at least about 15%,for example at least about 25%, at least about 50% or at least about75%, in BNP concentration.

The pulmonary hypertension condition according to the second embodimentcan comprise any one or more of the conditions in the WHO or Venice(2003) classification described above. In one aspect of the secondembodiment, the condition comprises PAH (WHO Group 1), for exampleidiopathic PAH, familial PAH or PAH associated with another disease.

In various aspects of the second embodiment, the subject at baselineexhibits PH (e.g., PAH) of at least WHO Class II, for example Class II,Class III or Class IV as described above.

In a more particular embodiment, the subject at baseline has a restingPAP of at least about 30 mmHg, for example at least about 35 mmHg or atleast about 40 mmHg.

In various aspects of the second embodiment, the subject can experience,during or following the treatment period, at least one of

-   -   (a) adjustment of one or more hemodynamic parameters indicative        of improvement of the pulmonary hypertension condition towards a        more normal level versus baseline;    -   (b) improvement in pulmonary function; illustratively an        increase in exercise capacity or lowering of BDI versus        baseline;    -   (c) improvement of one or more quality of life parameters versus        baseline; and/or    -   (d) maintenance of or movement to a lower WHO functional class.

For example, in one aspect the subject can experience improvement inpulmonary function versus baseline. Any measure of pulmonary functioncan be used; illustratively 6MWD is increased or BDI is lowered.

In one such aspect, 6MWD is improved from baseline by at least about 10m, for example, at least about 20 m or at least about 30 m. In manyinstances, the method of the present embodiment will be found effectiveto increase 6MWD by as much as 50 m or even more.

In another such aspect, BDI, illustratively as measured following a6MWT, is lowered from baseline by at least about 0.5 point. In manyinstances, the method of the present embodiment will be found effectiveto lower BDI by as much as 1 full index point or even more.

In another aspect, the subject can experience improvement in quality oflife, illustratively as measured by one or more of the health parametersrecorded in an SF-36® survey. For example, an improvement versusbaseline can be obtained in at least one of the SF-36 physical healthrelated parameters (physical health, role-physical, bodily pain and/orgeneral health) and/or in at least one of the SF-35 mental healthrelated parameters (vitality, social functioning, role-emotional and/ormental health). Such an improvement can take the form of an increase ofat least 1, for example at least 2 or at least 3 points, on the scalefor any one or more parameters.

In another aspect, the subject can experience maintenance or improvementin WHO functional class.

In a third embodiment, a method is provided for prolonging the life of asubject having a pulmonary hypertension condition, comprisingadministering to the subject ambrisentan at a dose and frequency and fora treatment period effective to increase life expectancy, from a time ofinitiation of treatment, by at least about 30 days, wherein, atbaseline, time from first diagnosis of the condition in the subject isnot greater than about 2 years. Variants and illustrative modalities ofthis method are as set forth for the second embodiment above.

In a fourth embodiment, a method is provided for extending time toclinical worsening in a subject having a pulmonary hypertensioncondition, comprising administering to the subject ambrisentan at a doseand frequency and for a treatment period effective to decrease theprobability of a clinical worsening event by at least about 25%,wherein, at baseline, time from first diagnosis of the condition in thesubject is not greater than about 2 years. Variants and illustrativemodalities of this method are as set forth for the second embodimentabove.

In any of the methods described hereinabove, the subject can be male orfemale. For example, ambrisentan can be administered to a female subjectaccording to any of the above methods, including the indicated variantsand illustrative modalities thereof. Alternatively, ambrisentan can beadministered to a male subject, for example a reproductively active malesubject, according to any of the above methods, including the indicatedvariants and illustrative modalities thereof.

In a fifth embodiment, a method is provided for treating a pulmonaryhypertension condition in a reproductively active male subject, themethod comprising administering a therapeutically effective amount ofambrisentan to the subject, wherein fertility of the subject is notsubstantially compromised. “Not substantially compromised” in thepresent context means that spermatogenesis is not substantially reducedby the treatment and that no hormonal changes are induced that areindicative of or associated with reduced spermatogenesis. Male fertilitycan be assessed directly, for example, by sperm counts from semensamples, or indirectly by changes in hormones such as folliclestimulating hormone (FSH), luteinizing hormone (LH), inhibin B andtestosterone.

In accordance with the fifth embodiment of the invention, administrationof ambrisentan as described hereinabove, including the indicatedvariants and illustrative modalities of such administration, hasgenerated no evidence of an adverse effect on male fertility as directlyor indirectly assessed.

In a sixth embodiment, a method is provided for treating PAH in asubject, comprising administering a therapeutically effective amount ofambrisentan to the subject, wherein the PAH is associated with one ormore of (a) a congenital heart defect, (b) portal hypertension, (c) useof a drug or toxin other than an anorexigen, (d) thyroid disorder, (e)glycogen storage disease, (f) Gaucher disease, (g) hereditaryhemorrhagic telangiectasia, (h) hemoglobinopathy, (i) myeloproliferativedisorder, (j) splenectomy, (k) pulmonary veno-occlusive disease and/or(l) pulmonary capillary hemangiomatosis. Variants and illustrativemodalities of this method are as set forth hereinabove.

In a seventh embodiment, a method is provided for treating a pulmonaryhypertension condition classified in WHO Groups 2-5 in a subject,comprising administering a therapeutically effective amount ofambrisentan to the subject. Variants and illustrative modalities of thismethod are as set forth hereinabove.

In one aspect of the seventh embodiment, the condition comprisesleft-sided atrial or ventricular heart disease and/or left-sidedvalvular heart disease.

In another aspect of the seventh embodiment, the condition is associatedwith one or more of chronic obstructive pulmonary disease (COPD),interstitial lung disease (ILD), sleep-disordered breathing, an alveolarhypoventilation disorder, chronic exposure to high altitude, adevelopmental abnormality, thromboembolic obstruction of proximal and/ordistal pulmonary arteries, a non-thrombotic pulmonary embolism,sarcoidosis, histiocytosis X, lymphangiomatosis, and/or compression ofpulmonary vessels.

In all the above embodiments of the invention, the ambrisentan can beadministered in monotherapy.

Alternatively, the ambrisentan can be administered in combinationtherapy with a second active agent effective for the treatment of thepulmonary hypertension condition or a condition related thereto. Whenambrisentan is administered concomitantly, one of skill in the art canreadily identify a suitable dose for any particular second active agentfrom publicly available information in printed or electronic form, forexample on the internet. Illustratively and without limitation, theambrisentan can be administered with a second active agent comprising atleast one drug selected from the group consisting of prostanoids,phosphodiesterase inhibitors (especially phosphodiesterase-5 (PDE5)inhibitors), endothelin receptor antagonists (ERAs) other thanambrisentan, calcium channel blockers, diuretics, anticoagulants, oxygenand combinations thereof.

Examples of drugs useful in combination therapy with ambrisentan areclassified and presented in several lists below. Some drugs are activeat more than one target; accordingly certain drugs may appear in morethan one list. Use of any listed drug in a combination is contemplatedherein, independently of its mode of action.

A suitable prostanoid can be illustratively selected from the followinglist:

beraprost

cicaprost

epoprostenol

iloprost

NS-304

PGE₁

prostacyclin

treprostinil

A suitable PDE5 inhibitor can illustratively be selected from thefollowing list:

sildenafil

tadalafil

vardenafil

An ERA other than ambrisentan can illustratively be selected from thefollowing list:

atrasentan

BMS 193884

bosentan

CI-1020

darusentan

S-0139

SB-209670

sitaxsentan

TA-0201

tarasentan

TBC-3711

VML-588

ZD-1611

A suitable calcium channel blocker can illustratively be selected fromthe following list:

Aryklalkylamines

-   -   bepridil    -   clentiazem    -   diltiazem    -   fendiline    -   gallopamil    -   mibefradil    -   prenylamine    -   semotiadil    -   terodiline    -   verapamil

Dihydropyridine Derivatives

-   -   amlodipine    -   aranidipine    -   barnidipine    -   benidipine    -   cilnidipine    -   efonidipine    -   elgodipine    -   felodipine    -   isradipine    -   lacidipine    -   lercanidipine    -   manidipine    -   nicardipine    -   nifedipine    -   nilvadipine    -   nimodipine    -   nisoldipine    -   nitrendipine    -   NZ 105

Piperazine Derivatives

-   -   cinnarizine    -   dotarizine    -   flunarizine    -   lidoflazine    -   lomerizine

Unclassified

-   -   bencyclane    -   etafenone    -   fantofarone    -   monatepil    -   perhexyline

Particularly suitable calcium channel blockers include amlodipine,diltiazem, felodipine, isradipine, nicardipine, nifedipine, nisoldipine,verapamil and combinations thereof.

A suitable diuretic can illustratively be selected from the followinglist:

Organomercurials

-   -   chlormerodrin    -   chlorothiazide    -   chlorthalidone    -   meralluride    -   mercaptomerin sodium    -   mercumatilin sodium    -   mercurous chloride    -   mersalyl

Purines

-   -   pamabrom    -   protheobromine    -   theobromine

Steroids

-   -   canrenone    -   oleandrin    -   spironolactone

Sulfonamide Derivatives

-   -   acetazolamide    -   ambuside    -   azosemide    -   bumetanide    -   butazolamide    -   chloraminophenamide    -   clofenamide    -   clopamide    -   clorexolone    -   disulfamide    -   ethoxzolamide    -   furosemide    -   mefruside    -   methazolamide    -   piretanide    -   torsemide    -   tripamide    -   xipamide

Thiazides and Analogs

-   -   althiazide    -   bendroflumethiazide    -   benzthiazide    -   benzylhydrochlorothiazide    -   buthiazide    -   chlorthalidone    -   cyclopenthiazide    -   cyclothiazide    -   ethiazide    -   fenquizone    -   hydrochlorothiazide    -   hydroflumethiazide    -   indapamide    -   methyclothiazide    -   metolazone    -   paraflutizide    -   polythiazide    -   quinethazone    -   teclothiazide    -   trichlormethiazide

Uracils

-   -   aminometradine

Unclassified

-   -   amiloride    -   Biogen BG 9719    -   chlorazanil    -   ethacrynic acid    -   etozolin    -   isosorbide    -   Kiowa Hakko KW 3902    -   mannitol    -   muzolimine    -   perhexyline    -   Sanofi-Aventis SR 121463    -   ticrynafen    -   triamterene    -   urea

In some embodiments, the diuretic if present comprises a thiazide orloop diuretic. Thiazide diuretics are generally not preferred where thepatient has a complicating condition such as diabetes or chronic kidneydisease, and in such situations a loop diuretic can be a better choice.

Particularly suitable thiazide diuretics include chlorothiazide,chlorthalidone, hydrochlorothiazide, indapamide, metolazone,polythiazide and combinations thereof. Particularly suitable loopdiuretics include bumetanide, furosemide, torsemide and combinationsthereof.

A suitable anticoagulant can illustratively be selected from thefollowing list:

acenocoumarol

ancrod

anisindione

bromindione

clorindione

coumetarol

cyclocumarol

dextran sulfate sodium

dicumarol

diphenadione

ethyl biscoumacetate

ethylidene dicoumarol

fluindione

heparin

hirudin

lyapolate sodium

pentosan polysulfate

phenindione

phenprocoumon

phosvitin

picotamide

tioclomarol

warfarin

Where the pulmonary hypertension condition is associated with anunderlying disease (for example CTD, HIV infection, COPD or ILD),ambrisentan can optionally be administered in combination therapy withone or more drugs targeting the underlying condition.

When ambrisentan is used in combination therapy with one or more drugs,the ambrisentan and at least one drug can be administered at differenttimes or at about the same time (at exactly the same time or directlyone after the other in any order). The ambrisentan and the second activedrug can be formulated in one dosage form as a fixed-dose combinationfor administration at the same time, or in two or more separate dosageforms for administration at the same or different times.

Separate dosage forms can optionally be co-packaged, for example in asingle container or in a plurality of containers within a single outerpackage, or co-presented in separate packaging (“common presentation”).As an example of co-packaging or common presentation, a kit iscontemplated comprising, in separate containers, ambrisentan and atleast one drug useful in combination with the ambrisentan. In anotherexample, the ambrisentan and the at least one drug useful in combinationtherapy with the ambrisentan are separately packaged and available forsale independently of one another, but are co-marketed or co-promotedfor use according to the invention. The separate dosage forms can alsobe presented to a patient separately and independently, for useaccording to the invention.

Typically at least the ambrisentan is provided in an orally deliverableformulation, for example a formulation adapted for oral delivery of aambrisentan dose of about 1 to about 600 mg/day, e.g., about 10 to about300 mg/day. The ambrisentan formulation can be adapted for any suitablefrequency of administration, but in one embodiment is adapted for once aday oral administration.

In one embodiment at least one of the drugs other than ambrisentan inthe combination is provided in an orally deliverable formulation; forexample, each of the drugs can be so provided, and each of the drugs canbe in a formulation adapted for once a day oral administration. Each ofthe drugs other than ambrisentan is typically present in the combinationin an amount providing an adequate to full dose of the drug. One ofskill in the art can readily identify a suitable dose for any particulardrug from publicly available information in printed or electronic form,for example on the internet.

Any two or more drugs in the combination can optionally be coformulatedto provide a fixed dose combination. For example, the ambrisentan can becoformulated with any one or more of the other drugs in the combination.

Mention of a particular drug or second active agent in the presentspecification and claims will be understood, except where the contextdemands otherwise, to include pharmaceutically acceptable salts, esters,prodrugs, metabolites, racemates and enantiomers of the drug, to theextent that such salts, esters, prodrugs, metabolites, racemates orenantiomers exist and are therapeutically effective.

EXAMPLES

The following examples are merely illustrative, and do not limit thisdisclosure in any way. Reference is made in the examples to statisticalanalysis and statistical significance of results. Such reference is madein the interest of full disclosure and does not constitute admissionthat statistical significance is a prerequisite for patentability of anyclaim herein. Reference is also made to “primary” and “secondary”endpoints or objectives of particular clinical trials. These endpointsor objectives should not necessarily be considered “primary” or“secondary” with respect to the present invention.

Examples 1 and 2 relate to Phase III clinical trials known as ARIES-2and ARIES-1, respectively. Certain results and other informationrelating to these trials have been mentioned in the following newsreleases and presented at various conferences as announced in some ofthese news releases. Each of the documents individually citedimmediately below is incorporated by reference in its entirety hereinwithout admission that any such document represents prior art to thepresent invention.

Myogen, Inc. News Release, Dec. 12, 2005(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=794738&highlight=).

Myogen, Inc. News Release, Feb. 13, 2006(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=815989&highlight=).

Myogen, Inc. News Release, Mar. 2, 2006(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=824548&highlight=)and ATS May 19-24, 2006 presentation announced therein.

Myogen, Inc. News Release, Apr. 10, 2006(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=840536&highlight=).

Myogen, Inc. News Release, May 3, 2006(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=851641&highlight=).

Myogen, Inc. News Release, May 8, 2006(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=853198&highlight=).

Myogen, Inc. News Release, May 24, 2006(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=860158&highlight=)and ATS 2006 presentation by Olschewski announced therein.

Myogen, Inc. News Release, Aug. 7, 2006(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=892987&highlight=).

Myogen, Inc. News Release, Sep. 5, 2006(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=902050&highlight=)and World Congress of Cardiology (Sep. 2-6, 2006, Barcelona, Spain)presentation by Galié announced therein; also abstract of Galiépresentation athttp://cic.escardio.org/AbstractDetails.aspx?id=41830&eevtid=15.

Myogen, Inc. News Release, Oct. 10, 2006(http://investor.myogen.com/phoenix.zhtml?c=135160&p=irol-newsArticle&ID=913787&highlight=)and CHEST 2006 presentation by Oudiz announced therein.

Myogen June 2006 presentation available atlibrary.corporate-ir.net/library/13/135/135160/items/203236/Junepresentation.pdf.

Example 1 Summary

The primary objective of this study was to determine the effect ofambrisentan on exercise capacity in subjects with PAH. The secondaryobjectives of this study were to evaluate effects of ambrisentan onother clinical measures of PAH, as well as safety and tolerability ofthe study drug.

Study drug was provided in round, biconvex, oral tablets that wereidentical in appearance. Three strengths of active study drug,containing 1 mg, 2.5 mg or 5 mg of ambrisentan, were used in this study.All study drug was packaged in blister cards. Subjects were instructedto take study drug once daily (q.d.) by mouth (p.o.) in the morning,with or without food.

The maximum study duration was up to 14 weeks from the time of initialscreening procedures to the final study visit (Week 12). Screeningprocedures were performed a maximum of 2 weeks prior to the first doseof study drug. The maximum duration of study drug treatment was 12weeks.

Placebo was indistinguishable from active treatment.

Methods Example 1 Patients

The number of subjects enrolled was 192 at 41 investigative sites.

Men and women, 18 years of age or older, with idiopathic PAH, PAHassociated with connective tissue disease (CTD), e.g., mixed CTD, CRESTsyndrome, systemic sclerosis (scleroderma), overlap syndrome or systemiclupus erythematosus, or PAH associated with anorexigen use or HIVinfection were enrolled in this study. Subjects were to have adocumented mean PAP ≧25 mmHg, PVR >3 mmHg/L/min, and PCWP or LVEDP <15mmHg. Subjects must have been able to walk a distance of at least 150 mbut no more than 450 m during 2 consecutive 6MWTs to be eligible forinclusion in the study.

Study Design and Treatment

After a 2 week screening period, eligible subjects were stratified basedon the underlying etiology of PAH (idiopathic or non-idiopathic) andwere randomized to 1 of 3 treatment groups (placebo, 2.5 mg or 5 mgambrisentan) in a ratio of 1:1:1. One blinded dose reduction waspermitted during the 12-week treatment period in the event of study drugintolerance (e.g., 5 mg to 2.5 mg, 2.5 mg to 1 mg, placebo to placebo).Subjects received a daily dose of 1 mg ambrisentan only if they reducedfrom the 2.5 mg dose group. Subjects were assessed for efficacy andsafety at monthly intervals.

Due to the placebo-controlled design of this study, there was a 1 in 3chance that a subject did not receive ambrisentan for a period of 12weeks. Therefore, after a minimum treatment period of 4 weeks, subjectswho met 2 or more of the following predefined early escape criteria mayhave been removed from the study:

-   -   (a) a decrease from baseline of at least 20% in 6MWD;    -   (b) an increase of 1 or more WHO functional class;    -   (c) worsening right ventricular failure (e.g., as indicated by        increased jugular venous pressure, new or worsening        hepatomegaly, ascites or peripheral edema);    -   (d) rapidly progressing cardiogenic, hepatic or renal failure;        and/or    -   (e) refractory systolic hypotension (systolic blood pressure <85        mmHg).

Subjects receiving placebo who were removed from the study due to 2 ormore early escape criteria were eligible to enter a long-term extensionstudy, and receive active treatment with ambrisentan.

Serum levels of alanine aminotransferase (ALT), aspartateaminotransferase (AST), alkaline phosphatase, gamma-glutamyltranspeptidase (GGT) and total bilirubin were closely monitored in allsubjects throughout the study. Female subjects of childbearing potentialwere required to undergo monthly pregnancy tests and to use a doublemethod of contraception to reduce risk of pregnancy during the course ofthe study. Male subjects were required to undergo complete semen andhormone analyses to evaluate potential effects of ambrisentan on malefertility.

After completion of the 12-week study, subjects were eligible to enrollinto the long-term extension study.

Efficacy Assessments

The primary efficacy endpoint was change from baseline in 6MWD evaluatedafter 12 weeks of treatment compared to placebo.

The secondary efficacy endpoints included:

-   -   (a) time to clinical worsening of PAH, as defined by the time        from randomization to the first occurrence of death, lung        transplantation, hospitalization for PAH, atrial septostomy,        study discontinuation due to addition of other PAH therapeutic        agents, or study discontinuation due to 2 or more early escape        criteria;    -   (b) change from baseline measured after 12 weeks of treatment        compared to placebo in:        -   (i) WHO functional class;        -   (ii) SF-36® health survey physical functioning scale;        -   (iii) BDI immediately following exercise; and/or        -   (iv) an assessment of the safety and tolerability of the            study drug; and    -   (c) change from baseline measured after 12 weeks of treatment        compared to placebo in plasma levels of ET-1, cTnT and BNP.

Safety Assessments

All adverse effects (AEs) reported during the course of the study werereported and summaries of all AEs were prepared showing frequencies andpercentages of:

-   -   (a) subjects with at least 1 AE;    -   (b) subjects with possibly or probably drug-related AEs;    -   (c) subjects with at least 1 serious AE (SAE);    -   (d) subjects with an AE leading to study discontinuation; and    -   (e) subjects who died.

Liver function test (LFT) assessments were separately summarized byseverity relative to the upper limit of normal (ULN) for ALT, AST,alkaline phosphatase and total bilirubin.

For subjects who were on anticoagulants at any point during the study(regular visit or between visits), coagulation tests (prothrombin time(PT), partial thromboplastin time (PTT) and international normalizedratio (INR)) were completed. In addition to summary statistics by studyvisit, changes in PT and INR were examined relative to changes inwarfarin-type anticoagulant dose. These analyses focused on the valuesat Week 0 and Week 12 and the percentage change from Week 0 to Week 12.

The results of semen samples and their normality or abnormality wereassessed by an independent male fertility expert and summarized throughfrequency counts and percentages by treatment. Descriptive statisticsfor male hormone data were prepared by treatment for the Week 0 and Week12 visits when data were collected. Change from Week 0 to Week 12 wasdetermined. The male fertility hormone results were analyzed incombination with the semen sample results by a second independent malefertility expert.

Frequency counts and percentages were used to summarize frequency ofnormal, abnormal but not clinically significant, and abnormal andclinically significant electrocardiogram (ECG) results for eachscheduled assessment time by treatment. All ECG data were digitallyrecorded and analyzed by a central reader. The following variables wereanalyzed: heart rate, RR and PR intervals, QRS duration, QT interval,QTcB, QTcF and ECG diagnostic variables. Descriptive statistics wereused to summarize ECG results by treatment group and by week of ECGassessment.

Descriptive statistics for vital signs were reported for each scheduledassessment time by treatment and for the change from pre-dose Week 0 toeach subsequent scheduled assessment by treatment.

Statistical Methods

A test of the null hypothesis of no treatment group difference in changefrom baseline in 6MWD with 62 subjects per group had approximately 90%power to detect an average placebo-adjusted treatment effect of 35 mbased on a 2-sample t-test and a standard deviation of 55 m.

The intention-to-treat (ITT) population was defined as all randomizedsubjects who received at least 1 dose of study drug. For the ITTpopulation, subjects were considered as belonging to their randomizedtreatment group, regardless of the actual treatment received.

The safety population was defined as all randomized subjects whoreceived at least 1 dose of study drug. Subjects were considered asbelonging to a treatment group according to the highest actual treatmentdose received. Any subject who received 5 mg ambrisentan on any day wasincluded in the 5 mg group for safety analyses in the entire study. Anysubject who received 2.5 mg ambrisentan on any day and never received 5mg ambrisentan on any day was included in the 2.5 mg group for safetyanalyses in the entire study. Otherwise, any subject who received onlyplacebo was included in the placebo group for safety analyses in thestudy.

The primary efficacy endpoint was the change from baseline in 6MWDevaluated after 12 weeks of treatment compared to placebo, where thelast observation was carried forward. Baseline 6MWD was defined as themean 6MWD of the last two 6MWTs prior to randomization.

Change from baseline for Weeks 4, 8 and 12 in each of the twoambrisentan treatment groups were compared to placebo. The mean changewas reported with 2-sided 95% confidence intervals (CIs) calculated bynormal theory. The primary comparison was the change from baseline toWeek 12. The Wilcoxon rank sum test stratified by idiopathic andnon-idiopathic PAH subjects was used for inference. A fixed sequenceapproach was used to control the type I error rate accounting for thetwo comparisons. The higher dose was first compared to placebo. Becausethe p-value from the Wilcoxon ranlc sum test was less than 0.05 for the5 mg ambrisentan group, the difference was considered significant, andthe lower dose was compared to placebo, again at the full 0.05 α-level.

The two ambrisentan dose groups were also combined and compared to theplacebo group. A p-value was reported, but for descriptive purposesonly, with no impact on the fixed sequence procedure used for comparingthe two individual dose groups to the placebo group.

If both ambrisentan dose groups were superior to placebo for the primaryendpoint, evaluation of the secondary endpoints was done by combiningthe subjects from the two dose groups for comparison to the placebogroup. However, if only the 5 mg group was significant for the primaryendpoint, evaluation of the secondary endpoints was done only for thatdose group. Secondary endpoint analyses were stratified by idiopathicand non-idiopathic PAH subjects.

The two most important secondary endpoints, time to clinical worseningof PAH and change in WHO functional class, were compared to placebousing a weighted version of Hommel's extension of the Simes test, withan overall α of 0.05. Time to clinical worsening was assigned a weightof 80% while change in WHO functional class received 20% of the weight.These two tests served as a gatekeeper, allowing the physicalfunctioning scale of the SF-36® health survey to be tested if at leastone of the first two secondary endpoints was significant. Lastly, theBDI was tested conditional on a significant result from the test of theSF-36® physical functioning scale.

Analyses of ET-1, cTnT, and BNP plasma levels were performed both forchange from baseline (treatment effect) and baseline impact on efficacy.Descriptive statistics were presented for the change from pre-dose Week0 to Week 12 by treatment.

Results Example 1 Patients Study Population

Disposition of randomized subjects is shown in Table 1.1.

TABLE 1.1 Subject disposition (% of randomized subjects) 2.5 mg 5 mgCombined Placebo ambrisentan ambrisentan ambrisentan (N = 65) (N = 64)(N = 63) (N = 127) Randomized 65 (100.0) 64 (100.0) 63 (100.0) 127(100.0) Completed 54 (83.1) 58 (90.6) 58 (92.1) 116 (91.3) Withdrew 11(16.9) 6 (9.4) 5 (7.9) 11 (8.7) Reasons for withdrawal: Adverse 3 (4.6)1 (1.6) 3 (4.8) 4 (3.1) event Clinical 1 (1.5) 0 (0.0) 0 (0.0) 0 (0.0)status did not improve or deteriorated Withdrawal 0 (0.0) 3 (4.7) 1(1.6) 4 (3.1) of consent Early escape 7 (10.8) 2 (3.1) 1 (1.6) 3 (2.4)

A total of 192 subjects, with a mean age of 50.9 years, received atleast 1 dose of study drug and were included in the ITT and safetypopulations. A majority of the subjects enrolled were female (74.5%) andCaucasian (84.9%). Approximately half (51.6%) of the subjects wereresidents of western Europe or Israel. The remainder of subjects wasevenly distributed throughout eastern Europe (24.0%) and South America(24.5%).

The number of years that PAH was present prior to participation in thestudy was calculated from the date that PAH was diagnosed until the datethat informed consent was signed. For subjects who had a diagnosis ofPAH confirmed at the screening visit for this study, the number of yearsof PAH present prior to this study was set to zero. The mean number ofyears that PAH was present prior to participation in this study wassimilar for the placebo (2.3±4.22 years) and 5 mg (2.9±6.10 years)groups but longer than that of the 2.5 mg (1.2±1.93 years) group. Themedian number of years that PAH was present was less than 1 year foreach treatment group: placebo, 0.38 years; 2.5 mg, 0.43 years; 5 mg,0.26 years.

Of the subjects enrolled, 65% had a diagnosis of idiopathic PAH prior toenrollment, and 35% had PAH associated with CTD, anorexigen use or HIVinfection (collectively designated non-idiopathic PAH herein);idiopathic and non-idiopathic PAH subjects were equally distributedbetween the treatment groups. Nearly all of the subjects had either WHOfunctional class II (44.8%) or class III (51.6%) symptoms. The mean(±standard deviation (SD)) baseline 6MWD for all subjects was348.4±84.46 m.

In general, demographic and baseline characteristics of the subjectsparticipating were well balanced between the treatment groups. There wasa difference in baseline 6MWD between subjects with WHO functional classII and WHO class III symptoms for both the placebo and combinedambrisentan groups: class II, 372.0 m and 379.1 m and class III, 330.2 mand 328.2 m, respectively.

The most frequently used concomitant medications were furosemide(37.0%), acenocoumarol (28.6%) and spironolactone (25.0%). There did notappear to be any differences in concomitant medication use across thetreatment groups.

Efficacy of Ambrisentan

Change in 6MWD from baseline to Week 12 in the ITT population is shownin Table 1.2.

TABLE 1.2 Change in 6MWD, meters 2.5 mg 5 mg Combined Placeboambrisentan ambrisentan ambrisentan Baseline 6MWD, 342.7 347.3 355.3 351.3 mean (SD)  (85.93)  (83.81) (84.45)  (83.89) Week 12 6MWD, 332.6369.6 404.7  387.0 mean (SD)  (130.42)  (128.31) (99.45)  (115.80)Change from −10.1 +22.2 +49.4  +35.7 baseline to  (93.79)  (82.67)(75.36)  (79.99) Week 12, mean (SD)

The primary efficacy endpoint was statistically significant for bothdoses of ambrisentan compared to placebo. The placebo-adjustedimprovement in mean 6MWD at Week 12 was +59.4 m (95% CI: +29.6 to +89.3m; p <0.001) for the 5 mg group and +32.3 m (95% CI: +1.5 to +63.1 m;p=0.022) for the 2.5 mg group. For subjects in the placebo group, mean6MWD showed a decrease from baseline (−10.1 m). For subjects receivingambrisentan, improvement in 6MWD compared to placebo was observed asearly as Week 8, and by Week 12 there was evidence of a dose response.

The key secondary endpoint of time to clinical worsening of PAHdemonstrated that ambrisentan (combined ambrisentan group) significantlydelayed the time to clinical worsening of PAH compared to placebo (p<0.001). In the placebo group, 21.5% of subjects experienced an event ofclinical worsening compared to 4.7% and 4.8% of subjects in the 2.5 mgand 5 mg dose groups, respectively. Furthermore, the hazard ratiodemonstrated an 80% reduction in the probability of clinical worseningoccurring at any given time for a subject receiving ambrisentan, whencompared to placebo.

The time to clinical worsening of PAH is displayed in FIG. 1 as aKaplan-Meier event-free curve through Week 12 for each treatment groupin the ITT population.

A summary of events defining clinical worsening by treatment group ispresented in Table 1.3.

TABLE 1.3 Clinical worsening events (% of ITT population) 2.5 mg 5 mgCombined Placebo ambrisentan ambrisentan ambrisentan Event (N = 65) (N =64) (N = 63) (N = 127) Death 3 (4.6) 2 (3.1) 0 (0.0) 2 (1.6) Lung trans-0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) plantation Hospitaliza- 9 (13.8) 3 (4.7)2 (3.2) 5 (3.9) tion for PAH Atrial 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)septostomy Study with- 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) drawal due toaddition of PAH treatment Escape criteria 7 (10.8) 2 (3.1) 1 (1.6) 3(2.4) Total subjects 14 (21.5) 3 (4.7) 3 (4.8) 6 (4.7) with ≧1 event

Of the 9 (13.8%) subjects in the placebo group hospitalized for PAH, 5were hospitalized for right heart failure or worsening right heartfailure. Comparatively, 5 (3.9%) subjects receiving ambrisentan werehospitalized for PAH, of whom 1 (in the 5 mg dose group) washospitalized for worsening right heart failure.

There were a total of 6 deaths reported during this study or within 30days of the last dose of study drug. In the placebo group, 4 (6.2%)subjects died, and 2 (3.1%) subjects in the 2.5 mg dose group died. Nosubjects receiving 5 mg ambrisentan died during the 12-week study. Fiveof the 6 deaths were captured as clinical worsening events; 3 (4.6%)placebo subjects and 2 (3.1%) subjects receiving 2.5 mg ambrisentan diedprior to completion of the 12-week treatment period. The sixth subjectwho dies was in the placebo group. This subject was hospitalized forclinical worsening of PAH, and the date of hospitalization was capturedas the date of clinical worsening for this subject. The subjectdiscontinued the study via the early escape procedure and subsequentlydied.

Change in WHO functional class from baseline to Week 12 in the ITTpopulation is shown in Table 1.4.

TABLE 1.4 Change in WHO functional class (% of ITT population) 2.5 mg 5mg Combined Change (no. Placebo ambrisentan ambrisentan ambrisentan ofclasses) (N = 65) (N = 64) (N = 63) (N = 127) −2 0 (0.0) 0 (0.0) 1 (1.6)1 (0.8) −1 11 (16.9) 10 (15.6) 8 (12.7) 18 (14.2) no change 42 (64.6) 51(79.7) 52 (82.5) 103 (81.1) +1 10 (15.4) 2 (3.1) 2 (3.2) 4 (3.1) +2 2(3.1) 1 (1.6) 0 (0.0) 1 (0.8)

A statistically significant difference between treatment groups in thechange in WHO functional class was not observed at Week 12. However, amore than 4-fold greater percentage of subjects in the placebo group(18.5%) deteriorated by at least 1 WHO class compared to subjects in thecombined ambrisentan group (3.9%).

The percentage of subjects at least maintaining their baseline WHOfunctional class at Week 12 was 81.5% in the placebo group, 95.3% in the2.5 mg dose group and 96.8% in the 5 mg dose group.

Change in SF-36® health survey parameters from baseline to Week 12 isshown in Table 1.5.

TABLE 1.5 Change in SF-36 ® health survey parameters, mean (SD) 2.5 mg 5mg Combined Parameter Placebo ambrisentan ambrisentan ambrisentanPhysical functioning −0.20 (7.14) +3.86 (7.14) +2.96 (6.81) +3.41 (6.96)Role-physical −0.15 (10.04) +5.87 (11.72) +7.61 (10.41) +6.74 (11.07)Bodily pain −0.24 (12.02) +2.34 (11.87) +0.46 (9.99) +1.40 (10.96)General health +1.37 (6.24) +3.84 (6.71) +4.95 (8.05) +4.40 (7.40)Vitality −0.01 (9.11) +4.07 (9.12) +5.21 (8.79) +4.64 (8.94) Socialfunctioning +2.45 (10.54) +4.55 (9.72) +4.85 (11.89) +4.70 (10.81)Role-emotional −1.58 (14.25) +3.11 (12.90) +8.15 (14.43) +5.63 (13.86)Mental health +2.53 (10.79) +4.98 (9.70) +4.03 (10.13) +4.50 (9.88)Physical component summary −0.15 (7.29) +3.78 (7.63) +2.97 (7.79) +3.38(7.69) Mental component summary +1.27 (11.29) +4.05 (10.30) +6.28(11.64) +5.17 (11.00)

A statistically significant increase was observed for the combinedambrisentan group (3.41±6.96) in the physical functioning scale of theSF-36® health survey compared to placebo (−0.20±8.14, p=0.005).Improvements in the physical functioning scale were also demonstratedfor both the 2.5 mg and 5 mg dose groups compared to placebo.Furthermore, increases were observed in several other SF-36® scalesincluding role-physical, general health, vitality and role-emotionalscales.

A statistically significant improvement in BDI was observed at Week 12for the combined ambrisentan group, with a placebo-adjusted BDI of −1.1(95% CI: −1.8 to −0.4; p=0.019). Improvements in BDI were observed forboth the 2.5 mg and 5 mg dose groups compared to placebo. For subjectsin the placebo group, mean BDI increased (worsened) from baseline by+0.82. In contrast, in the 2.5 mg and 5 mg ambrisentan dose groups meanBDI decreased (improved) from baseline (−0.20 and −0.36, respectively).

At Week 12, the geometric mean percent change in plasma ET-1 decreasedby 4% (95% CI: 0.68 to 1.36) in the placebo group; whereas the geometricmean percent change in plasma ET-1 increased from baseline by 19% (95%CI: −12% to 61%; p=0.193 versus placebo) in the 2.5 mg group and by 72%(95% CI: 32% to 125%; p=0.004 versus placebo) in the 5 mg group. Thechange from baseline was substantially greater than placebo for the 5 mggroup, but not for the 2.5 mg group.

At baseline, approximately 90% of plasma cTnT concentrations were belowthe level of quantification (0.01 ng/ml). Changes in cTnT concentrationsduring the 12-week study were minor and not remarkably different fromzero.

At Week 12, the geometric mean percent change plasma BNP increased by13% (95% CI: −6% to 36%) in the placebo group. In contrast, thegeometric mean plasma BNP decreased from baseline by 29% (95% CI: −44%to −9%; p=0.002 versus placebo) in the 2.5 mg group and by 30% (95% CI:−47% to −9%; p=0.002 versus placebo) in the 5 mg group. The decreasefrom baseline was substantially greater than placebo for the 2.5 mggroup and the 5 mg group.

Efficacy by Subgroup

Improvements in 6MWD were observed for both WHO functional class I/IIand WHO functional class III/IV subjects at Week 12. For the class I/IIsubgroup, the placebo-adjusted 6MWD increase from baseline at Week 12was +44.1 m and +67.7 m for the 2.5 mg and 5 mg dose groups,respectively. For the class III/IV subgroup, the placebo-adjusted 6MWDincrease from baseline at Week 12 was +17.6 m and +51.8 m for the 2.5 mgand 5 mg dose groups, respectively.

Improvements in 6MWD at Week 12 were observed in both ambrisentan dosegroups for the idiopathic PAH subgroup and in the 5 mg dose group forthe non-idiopathic PAH subgroup. For the idiopathic PAH subgroup, theplacebo-adjusted 6MWD increase from baseline at Week 12 was +56.3 m and+75.7 m for the 2.5 mg and 5 mg dose groups, respectively. For thenon-idiopathic PAH subgroup, the placebo-adjusted 6MWD change frombaseline at Week 12 was −12.6 m and +29.5 m for the 2.5 mg and 5 mg dosegroups, respectively.

Improvements in 6MWD at Week 12 were observed in both ambrisentan dosegroups for the female subjects. For female subjects, theplacebo-adjusted 6MWD increase from baseline at Week 12 was +42.5 m and+75.7 m for the 2.5 mg and 5 mg dose groups, respectively. For malesubjects, the placebo-adjusted 6MWD change from baseline at Week 12 was+6.8 m and +2.7 m for the 2.5 mg and 5 mg dose groups, respectively.

Improvements in 6MWD at Week 12 were observed in both ambrisentan dosegroups for the eastern European and South American populations and inthe 5 mg dose group for the western European/Israel population. For theeastern European subgroup, the placebo-adjusted 6MWD increase frombaseline at Week 12 was +66.1 and +88.0 m for the 2.5 mg and 5 mg dosegroups respectively. For the South American subgroup, theplacebo-adjusted 6MWD increase from baseline at Week 12 was +50.5 and+79.5 m for the 2.5 mg and 5 mg dose groups respectively. For thewestern European/Israel subgroup, the placebo-adjusted 6MWD increasefrom baseline at Week 12 was +3.0 and +39.4 m for the 2.5 mg and 5 mgdose groups, respectively.

Safety Results

A summary of adverse events recorded is shown in Table 1.6.

TABLE 1.6 Global summary of adverse events (% of safety population) 2.5mg 5 mg Combined Placebo ambrisentan ambrisentan ambrisentan Subjects (N= 65) (N = 64) (N = 63) (N = 127) with at least 52 (80.0) 47 (73.4) 46(73.0) 93 (73.2) 1 AE with at least 22 (33.8) 19 (29.7) 21 (33.3) 40(31.5) 1 related AE with at least 15 (23.1) 8 (12.5) 6 (9.5) 14 (11.0) 1SAE with an AE 6 (9.2) 3 (4.7) 4 (6.3) 7 (5.5) leading to study dis-continuation who discon- 7 (10.8) 2 (3.1) 1 (1.6) 3 (2.4) tinued thestudy via early escape who died 4 (6.2) 2 (3.1) 0 (0.0) 2 (1.6)

During this 12-week study, 80.0% of the subjects in the placebo groupexperienced at least 1 AE. Similarly, 73.4% of subjects in the 2.5 mgdose group and 73.0% of subjects in the 5 mg dose group experienced atleast 1 AE during the study.

Overall, more subjects in the placebo group compared to the ambrisentangroups prematurely discontinued from the study due to death, SAEs, AEs,and/or the early escape procedure.

In general, more AEs were assessed as moderate and severe in the placebogroup (43.1% and 18.5%, respectively) compared to the combinedambrisentan group (26.8% and 7.9%, respectively).

None of the 127 subjects who received ambrisentan developed any elevatedserum aminotransferase concentrations >3.0×ULN, compared to 1 subject inthe placebo group, and there were no notable mean changes from baselineat Week 12 for serum ALT and AST, and no differences between treatmentgroups. Furthermore, there was a notable decrease in mean totalbilirubin and mean alkaline phosphatase that appeared to bedose-dependent.

Mean uric acid increased at Week 12 in the placebo group (+34.1 μmol/l);whereas there was a substantial mean decrease in uric acid (−19.1μmol/l) in the combined ambrisentan group.

The analysis of male fertility hormones in combination with a limitednumber of subjects (n=6) providing serial semen samples did not suggestthat ambrisentan was associated with an adverse effect on malereproductive potential.

More specifically, changes over baseline in follicle stimulating hormone(FSH) concentration at Week 12 were small, ranging from −0.25 IU/liter(placebo group) to +0.58 IU/liter (2.5 mg dose group). Although thebaseline FSH concentrations for the placebo and 5 mg dose groups(7.6±8.34 IU/liter and 7.6±5.69 IU/liter, respectively) suggestpossibility of some spermatogenic dysfunction prior to the first dose ofstudy drug, the changes observed during the study were unlikely to be ofsubstantial clinical relevance.

Minor increases in luteinizing hormone (LH) concentration, ranging from0.16 to 0.58 IU/liter, were observed in all treatment groups, with noapparent difference between groups.

Increases from baseline in mean inhibin B concentration at Week 12 wereobserved for the placebo group (139.6±95.34 pg/ml) and the 5 mg dosegroup (131.2±98.77 pg/ml), but a decrease was observed in the 2.5 mgdose group (−43.2±36.52 pg/ml). Therefore, changes in inhibin B were notdose-dependent. Based on expert opinion, none of the mean inhibin Bconcentrations measured at baseline and Week 12 indicated presence ordevelopment of spermatogenic dysfunction.

Subjects in the placebo group had a minor increase (0.66±3.904 nmol/l)in testosterone concentration over the 12-week study; however,testosterone concentrations decreased in an apparently dose-dependentmanner in subjects receiving ambrisentan (2.5 mg, −0.09±4.595 nmol/l; 5mg, −2.61±6.962 nmol/l. The data were variable and the median valuesindicated little change. Furthermore, the Week 12 data did not representa decrease below the lower range of normal (10.41 nmol/l).

Discussion Example 1

The ambrisentan treatment benefit observed by the primary and secondaryendpoints of this study was robust, internally consistent, andclinically relevant.

Both doses demonstrated a statistically significant and clinicallyrelevant improvement in 6MWD that was associated with a significantdecrease in BDI. The improvement in 6MWD was nearly twice as large inthe 5 mg dose group compared to the 2.5 mg dose group, and improvementsin 6MWD were consistently dose-responsive for most subgroups evaluated.Furthermore, plasma BNP, a molecular marker that has been shown todecrease in patients with PAH who demonstrate improvements in 6MWD orhemodynamics, was substantially reduced with ambrisentan treatment.Ultimately, these symptomatic improvements resulted in a patient'sself-assessment of an overall better quality of life, as measured bystatistically significant improvements in several scales of the SF-36®health survey.

In addition to the symptomatic improvements observed for exercisecapacity and dyspnea, there was a more than 4-fold greater percentage ofsubjects in the placebo group who deteriorated by at least 1 WHO classcompared to subjects in the ambrisentan groups. Furthermore, there was asignificant decrease in disease progression for subjects receivingambrisentan compared to placebo as measured by the time to clinicalworsening endpoint. This was associated with an 80% decrease in the riskof clinical worsening over the 12-week study for the ambrisentan groupcompared to placebo. The delay in disease progression was also apparentby the lower number of subjects in the ambrisentan treatment groupscompared to placebo for each of the following safety categories: death,SAEs, AEs leading to discontinuation and early escapes. Finally, themost frequent AE observed in this study was right ventricular failure,an indicator of disease progression, which was reported in more than 3times the percentage of subjects in the placebo group compared to thecombined ambrisentan treatment group.

In general, ambrisentan was well tolerated, as demonstrated by the lackof dose reduction and AEs leading to discontinuation. The most frequentAEs of clinical concern observed for subjects receiving ambrisentan wereheadache and palpitations. For the most part, these events were mild inseverity and did not lead to study discontinuation. Peripheral edema,which has been reported frequently with other ERAs was observed at asimilar or lower frequency in the ambrisentan groups compared toplacebo. None of the 127 subjects that received ambrisentan developedelevated serum aminotransferase concentrations >3×ULN, and there were noincreases in mean ALT or AST concentrations for either ambrisentan dosegroup. Furthermore, there appeared to be a dose-dependent decrease inmean total bilirubin and mean alkaline phosphatase. Decreases inhemoglobin concentration were observed early in the study and did notdecrease further with continued treatment.

In conclusion, the treatment benefits observed for the primary andsecondary endpoints of this study were robust, internally consistent,and clinically relevant. Ambrisentan was well tolerated, was associatedwith a manageable safety profile, and delayed disease progression,indicating a positive risk-to-benefit profile.

Example 2 Summary

The primary objective of this study was to determine the effect ofambrisentan on exercise capacity in subjects with pulmonary arterialhypertension (PAH). The secondary objectives of this study were toevaluate effects of ambrisentan on other clinical measures of PAH, aswell as safety and tolerability of the study drug.

Study drug was provided in round, biconvex, oral tablets that wereidentical in appearance. Three strengths of active study drug containing2.5 mg, 5 mg or 10 mg of ambrisentan were used in this study. All studydrug was packaged in blister cards. Subjects were instructed to takestudy drug once daily (q.d.) by mouth (p.o.) in the morning, with orwithout food.

The maximum study duration was up to 14 weeks from the time of initialscreening procedures to the final study visit (Week 12). Screeningprocedures were performed a maximum of 2 weeks prior to the first doseof study drug. The maximum duration of study drug treatment was 12weeks.

Placebo was indistinguishable from active treatment.

Methods Example 2 Patients

The number of subjects enrolled was 202 at 46 investigative sites.

Men and women, 18 years of age or older, with idiopathic PAH, PAHassociated with CTD, e.g., mixed CTD, CREST syndrome, systemic sclerosis(scleroderma), overlap syndrome or systemic lupus erythematosus, or PAHassociated with anorexigen use or HIV infection were enrolled in thisstudy. Subjects were to have a documented mean PAP >25 mmHg, PVR >3mmHg/L/min, and PCWP or LVEDP <15 mmHg. Subjects must have been able towalk a distance of at least 150 m but no more than 450 m during 2consecutive 6MWTs to be eligible for inclusion in the study.

Study Design and Treatment After a 2 week screening period, eligiblesubjects were stratified based on the underlying etiology of PAH(idiopathic or non-idiopathic) and were randomized to 1 of 3 treatmentgroups (placebo, 5 mg or 10 mg ambrisentan) in a ratio of 1:1:1. Oneblinded dose reduction was permitted during the 12-week treatment periodin the event of study drug intolerance (e.g., 10 mg to 5 mg, 5 mg to 2.5mg, placebo to placebo). Subjects received a daily dose of 2.5 mgambrisentan only if they reduced from the 5 mg dose group. Subjects wereassessed for efficacy and safety at monthly intervals.

Due to the placebo-controlled design of this study, there was a 1 in 3chance that a subject did not receive ambrisentan for a period of 12weeks. Therefore, after a minimum treatment period of 4 weeks, subjectswho met 2 or more of the following predefined early escape criteria mayhave been removed from the study:

-   -   (a) a decrease from baseline of at least 20% in 6MWD;    -   (b) an increase of 1 or more WHO functional class;    -   (c) worsening right ventricular failure (e.g., as indicated by        increased jugular venous pressure, new or worsening        hepatomegaly, ascites or peripheral edema);    -   (d) rapidly progressing cardiogenic, hepatic or renal failure;        and/or    -   (e) refractory systolic hypotension (systolic blood pressure <85        mmHg).

Subjects receiving placebo who were removed from the study due to 2 ormore early escape criteria were eligible to enter a long-term extensionstudy, and receive active treatment with ambrisentan.

Serum levels of alanine aminotransferase (ALT), aspartateaminotransferase (AST), alkaline phosphatase, gamma-glutamyltranspeptidase (GGT) and total bilirubin were closely monitored in allsubjects throughout the study. Female subjects of childbearing potentialwere required to undergo monthly pregnancy tests and to use a doublemethod of contraception to reduce risk of pregnancy during the course ofthe study. Male subjects were required to undergo complete semen andhormone analyses to evaluate potential effects of ambrisentan on malefertility.

After completion of the 12-week study, subjects were eligible to enrollinto the long-term extension study.

Efficacy Assessments

The primary efficacy endpoint was change from baseline in 6MWD evaluatedafter 12 weeks of treatment compared to placebo.

The secondary efficacy endpoints included:

-   -   (a) time to clinical worsening of PAH, as defined by the time        from randomization to the first occurrence of death, lung        transplantation, hospitalization for PAH, atrial septostomy,        study discontinuation due to addition of other PAH therapeutic        agents, or study discontinuation due to 2 or more early escape        criteria;    -   (b) change from baseline measured after 12 weeks of treatment        compared to placebo in:        -   (i) WHO functional class;        -   (ii) SF-36® health survey physical functioning scale;        -   (iii) BDI immediately following exercise; and/or        -   (iv) an assessment of the safety and tolerability of the            study drug; and    -   (c) change from baseline measured after 12 weeks of treatment        compared to placebo in plasma levels of ET-1, BNP and cTnT.

Safety Assessments

All adverse effects (AEs) reported during the course of the study werereported and summaries of all AEs were prepared showing frequencies andpercentages of:

-   -   (a) subjects with at least 1 AE;    -   (b) subjects with possibly or probably drug-related AEs;    -   (c) subjects with at least 1 serious AE (SAE);    -   (d) subjects with an AE leading to study discontinuation; and    -   (e) subjects who died.

Liver function test (LFT) assessments were separately summarized byseverity relative to the upper limit of normal (ULN) for ALT, AST,alkaline phosphatase and total bilirubin.

For subjects who were on anticoagulants at any point during the study(regular visit or between visits), coagulation tests (PT, PTT and INR)were completed. In addition to summary statistics by study visit,changes in PT and INR were examined relative to changes in warfarin-typeanticoagulant dose. These analyses focused on the values at Week 0 andWeek 12 and the percentage change from Week 0 to Week 12.

The results of semen samples and their normality or abnormality wereassessed by an independent male fertility expert and summarized throughfrequency counts and percentages by treatment. Descriptive statisticsfor male hormone data were prepared by treatment for the Week 0 and Week12 visits when data were collected. Change from Week 0 to Week 12 wasdetermined. The male fertility hormone results were analyzed incombination with the semen sample results by a second independent malefertility expert.

Frequency counts and percentages were used to summarize frequency ofnormal, abnormal but not clinically significant, and abnormal andclinically significant ECG results for each scheduled assessment time bytreatment. All ECG data were digitally recorded and analyzed by acentral reader. The following variables were analyzed: heart rate, RRand PR intervals, QRS duration, QT interval, QTcB, QTcF and ECGdiagnostic variables. Descriptive statistics were used to summarize ECGresults by treatment group and by week of ECG assessment.

Descriptive statistics for vital signs were reported for each scheduledassessment time by treatment and for the change from pre-dose Week 0 toeach subsequent scheduled assessment by treatment.

Statistical Methods

A test of the null hypothesis of no treatment group difference in changefrom baseline in 6MWD with 62 subjects per group had approximately 90%power to detect an average placebo-adjusted treatment effect of 35 mbased on a 2-sample t-test and a standard deviation of 55 m.

The intention-to-treat (ITT) population was defined as all randomizedsubjects who received at least 1 dose of study drug. For the ITTpopulation, subjects were considered as belonging to their randomizedtreatment group, regardless of the actual treatment received.

The safety population was defined as all randomized subjects whoreceived at least 1 dose of study drug. Subjects were considered asbelonging to a treatment group according to the highest actual treatmentdose received. Any subject who received 10 mg ambrisentan on any day wasincluded in the 10 mg group for safety analyses in the entire study. Anysubject who received 5 mg ambrisentan on any day and never received 10mg ambrisentan on any day was included in the 5 mg group for safetyanalyses in the entire study. Otherwise, any subject who received onlyplacebo was included in the placebo group for safety analyses in thestudy.

The primary efficacy endpoint was the change from baseline in 6MWDevaluated after 12 weeks of treatment compared to placebo, where thelast observation was carried forward. Baseline 6MWD was defined as themean 6MWD of the last two 6MWTs prior to randomization.

Change from baseline for Weeks 4, 8 and 12 in each of the twoambrisentan treatment groups were compared to placebo. The mean changewas reported with 2-sided 95% confidence intervals (CIs) calculated bynormal theory. The primary comparison was the change from baseline toWeek 12. The Wilcoxon rank sum test stratified by idiopathic andnon-idiopathic PAH subjects was used for inference. A fixed sequenceapproach was used to control the type I error rate accounting for thetwo comparisons. The higher dose was first compared to placebo. Becausethe p-value from the Wilcoxon rank sum test was less than 0.05 for the 5mg ambrisentan group, the difference was considered significant, and thelower dose was compared to placebo, again at the full 0.05 α-level.

The two ambrisentan dose groups were also combined and compared to theplacebo group. A p-value was reported, but for descriptive purposesonly, with no impact on the fixed sequence procedure used for comparingthe two individual dose groups to the placebo group.

If both ambrisentan dose groups were superior to placebo for the primaryendpoint, evaluation of the secondary endpoints was done by combiningthe subjects from the two dose groups for comparison to the placebogroup. However, if only the 10 mg group was significant for the primaryendpoint, evaluation of the secondary endpoints was done only for thatdose group. Secondary endpoint analyses were stratified by idiopathicand non-idiopathic PAH subjects.

The two most important secondary endpoints, time to clinical worseningof PAH and change in WHO functional class, were compared to placebousing a weighted version of Hommel's extension of the Simes test, withan overall α of 0.05. Time to clinical worsening was assigned a weightof 80% while change in WHO functional class received 20% of the weight.These two tests served as a parallel gatekeeper, allowing the physicalfunctioning scale of the SF-36® health survey to be tested if at leastone of the first two secondary endpoints was significant. Lastly, theBDI was tested conditional on a significant result from the test of theSF-36® physical functioning scale.

Additional measures of interest included change from baseline measuredafter 12 weeks of treatment compared to placebo in ET-1, BNP and cTnT.

Results Example 2 Patients Study Population

Disposition of randomized subjects is shown in Table 2.1.

TABLE 2.1 Subject disposition (% of randomized subjects) 5 mg 10 mgCombined Placebo ambrisentan ambrisentan ambrisentan (N = 67) (N = 67)(N = 68) (N = 135) Randomized 67 (100.0) 67 (100.0) 68 (100.0) 135(100.0) Completed 57 (85.1) 63 (94.0) 63 (92.6) 126 (93.3) Withdrew 10(14.9) 4 (6.0) 5 (7.4) 9 (6.7) Reasons for withdrawal: Adverse 1 (1.5) 1(1.5) 1 (1.5) 2 (1.5) event Withdrawal 1 (1.5) 0 (0.0) 0 (0.0) 0 (0.0)of consent Treatment 1 (1.5) 0 (0.0) 0 (0.0) 0 (0.0) with other PAHthera- peutic agents Other 1 (1.5) 2 (3.0) 1 (1.5) 3 (2.1) Early escape4 (6.0) 0 (0.0) 2 (2.9) 2 (1.5)

A total of 201 subjects, with a mean age of 50.1 years, received atleast 1 dose of study drug and were included in the ITT and safetypopulations. A majority of the subjects enrolled were female (83.6%) andCaucasian (69.2%). More than two-thirds (68.7%) of the subjects wereresidents of the U.S.; the others were distributed in Central and SouthAmerica (20.9%) and the rest of the world (10.4% in Australia, Austria,Hungary and Italy).

The number of years that PAH was present prior to participation in thestudy was calculated from the date that PAH was diagnosed until the datethat informed consent was signed. For subjects who had a diagnosis ofPAH confirmed at the screening visit for this study, the number of yearsof PAH present prior to this study was set to zero. The mean number ofyears that PAH was present prior to participation in this study wasslightly longer for the placebo (2.14±3.63 years) than for the 5 mg(1.86±4.36 years) and 10 mg (1.40±2.39 years) groups. The median numberof years that PAH was present was less than 1 year for each treatmentgroup: placebo, 0.54 years; 5 mg, 0.33 years; 10 mg, 0.60 years.

Of the subjects enrolled, 63% had a diagnosis of idiopathic PAH prior toenrollment, and 37% had PAH associated with CTD, anorexigen use or HIVinfection; idiopathic and non-idiopathic PAH subjects were equallydistributed between the treatment groups. Nearly all of the subjects hadeither WHO functional class II (32.3%) or class III (58.2%) symptoms atbaseline; only a small percentage of subjects had WHO class I (2.5%) orIV (7.0%) symptoms at baseline. The mean (±standard deviation (SD))baseline 6MWD for all subjects was 341.0±75.80 m, and the mean baselineBDI was 3.8±2.02.

In general, demographic and baseline characteristics of the subjectsparticipating were well balanced between the treatment groups. However,there were more class IV subjects in the 5 mg (9.0%) and 10 mg (10.4%)dose groups than in the placebo group (1.5%). There was also adifference in baseline 6MWD between WHO class I/II and WHO class III/IVsubjects for both the placebo and combined ambrisentan groups: classI/II, 377.5 m and 372.0 m; and class III/IV, 320.6 m and 324.6 m,respectively.

The most frequently used concomitant medications were furosemide(47.3%), warfarin sodium (36.8%) and oxygen (26.4%). Minor differenceswere observed between dose groups in the use of concomitant medications.

Efficacy of Ambrisentan

Change in 6MWD from baseline to Week 12 in the ITT population is shownin Table 2.2.

TABLE 2.2 Change in 6MWD, meters 5 mg 10 mg Combined Placebo ambrisentanambrisentan ambrisentan Baseline 6MWD, 341.9  339.6  341.5  340.5  mean(SD) (73.47) (76.68) (78.28) (77.20) Change from −7.8  +22.8  +43.6 +33.2  baseline to (78.88) (82.98) (65.91) (75.37) Week 12, mean (SD)

The primary efficacy endpoint was statistically significant for bothdoses of ambrisentan compared to placebo. The placebo-adjustedimprovement in mean 6MWD at Week 12 was +51.4 m (95% CI: 26.6 to 76.2; p<0.001) for the 10 mg group and +30.6 m (95% CI: 2.9 to 58.3; p=0.008)for the 5 mg group. For subjects in the placebo group, the mean 6MWDdecreased from baseline (−7.8 m). For subjects receiving ambrisentan,improvement in 6MWD compared to placebo was observed as early as Week 4,and by Week 8 there was evidence of a dose response.

The secondary endpoint of time to clinical worsening of PAH demonstratedthat ambrisentan (combined ambrisentan group) did not significantlydelay the time to clinical worsening of PAH compared to placebo.However, twice as many subjects in the placebo group (n=6) had an eventof clinical worsening compared to each of the ambrisentan dose groups (3subjects each in the 5 mg and 10 mg dose groups). Furthermore, thehazard ratio showed a 50% reduction in the probability of clinicalworsening occurring at any given time for a subject receivingambrisentan, when compared to placebo.

The time to clinical worsening of PAH is displayed in FIG. 2 as aKaplan-Meier event-free curve through Week 12 for each treatment groupin the ITT population. The Kaplan-Meier curve decreases sharply in the10 mg dose group after 12 weeks due to a single event that occurredafter most subjects had completed the study.

A summary of events defining clinical worsening by treatment group ispresented in Table 2.3.

TABLE 2.3 Clinical worsening events (% of ITT population) 5 mg 10 mgCombined Placebo ambrisentan ambrisentan ambrisentan Event (N = 67) (N =67) (N = 68) (N = 135) Death 2 (3.0) 1 (1.5) 1 (1.5) 2 (1.5) Lung trans-0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) plantation Hospitaliza- 2 (3.0) 2 (3.0)2 (3.0) 4 (3.0) tion for PAH Atrial 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)septostomy Study 1 (1.5) 0 (0.0) 1 (1.5) 1 (0.7) discontinua- tion dueto addition of PAH treatment Escape 3 (4.5) 0 (0.0) 2 (3.0) 2 (1.5)criteria Total subjects 6 (9.0) 3 (4.5) 3 (4.5) 6 (4.5) with ≧1 event

Of the 2 (3.0%) subjects in the placebo group hospitalized for PAH, 1was hospitalized for right heart failure and 1 for right ventricularfailure. Comparatively, 4 (3.0%) subjects receiving ambrisentan werehospitalized for PAH, of whom 2 (1 each in the 5 mg and 10 mg dosegroups) were hospitalized for worsening right heart failure, and theother 2 for increased shortness of breath with increased peripheraledema (5 mg) and worsening PAH with severe peripheral edema (10 mg).

There were a total of 4 deaths reported during this study or within 30days of the last dose of study drug. In the placebo group, 2 (3.0%)subjects died, and 1 (1.5%) subject each in the 5 mg and 10 mg dosegroups died. All 4 deaths were captured as clinical worsening events.

Change in WHO functional class from baseline to Week 12 in the ITTpopulation is shown in Table 2.4.

TABLE 2.4 Change in WHO functional class (% of ITT population) 5 mg 10mg Combined Change (no. Placebo ambrisentan ambrisentan ambrisentan ofclasses) (N = 67) (N = 67) (N = 68) (N = 135) −2 1 (1.5) 1 (1.5) 5 (7.5)6 (4.5) −1 15 (22.4) 18 (26.9) 15 (22.4) 33 (24.6) no change 40 (59.7)47 (70.1) 44 (65.7) 91 (67.9) +1 11 (16.4) 1 (1.5) 3 (4.5) 4 (3.0) +2 0(0.0) 0 (0.0) 0 (0.0) 0 (0.0)

The combined ambrisentan group demonstrated a clinically relevantimprovement in WHO functional class at Week 12 compared to placebo(p=0.036); similar trends were observed for each ambrisentan treatmentgroup. Due to the multiple comparisons procedure, a statisticallysignificant improvement compared to placebo could not be stated for thissecondary endpoint. However, a more than 5-fold greater percentage ofsubjects in the placebo group (16.4%) deteriorated by at least 1 WHOclass compared to subjects in the combined ambrisentan group (3.0%). Inaddition, a 3-fold greater percentage of subjects in the combinedambrisentan group (4.5%) had an improvement of 2 WHO classes compared tosubjects in the placebo group (1.5%).

The percentage of subjects at least maintaining their baseline WHOfunctional class at Week 12 was 83.6% in the placebo group, 98.5% in the5 mg dose group and 95.5% in the 10 mg dose group.

Change in SF-36® health survey parameters from baseline to Week 12 isshown in Table 2.5.

TABLE 2.5 Change in SF-36 ® health survey parameters, mean (SD) 5 mg 10mg Combined Parameter Placebo ambrisentan ambrisentan ambrisentanPhysical functioning +2.31 ± 7.65  +3.86 ± 7.14  +4.52 ± 7.16  +4.10 ±8.39  Role-physical +2.81 ± 11.36 +4.22 ± 10.52 +6.67 ± 10.35 +5.45 ±10.47 Bodily pain +0.22 ± 10.70 −1.43 ± 13.21 +2.26 ± 12.22 +0.42 ±12.81 General health +1.94 ± 7.50  +0.08 ± 8.45  +3.25 ± 8.81  +1.66 ±8.74  Vitality +2.38 ± 10.06 +2.38 ± 10.06 +5.03 ± 10.07 +3.71 ± 10.11Social functioning +2.31 ± 11.60 +1.11 ± 13.63 +4.11 ± 11.77 +2.61 ±12.78 Role-emotional +2.84 ± 12.63 +1.41 ± 13.95 +2.98 ± 17.37 +2.19 ±15.71 Mental health +0.27 ± 8.09  +0.81 ± 9.67  +1.55 ± 12.66 +1.18 ±11.23 Physical component summary +1.82 ± 9.25  +1.88 ± 8.68  +4.79 ±7.90  +3.34 ± 8.40  Mental component summary +1.56 ± 9.00  +0.50 ± 10.50+2.11 ± 13.17 +1.30 ± 11.89

An increase in the physical function scale of the SF-36® Health Surveywas observed in the combined ambrisentan group at Week 12 (4.10±8.39);however, this increase was not significantly different from placebo(2.31±7.65). For most of the SF-360 scales there was a general trend ofgreater increases for the 10 mg group compared to the 5 mg and placebogroups.

A clinically relevant improvement in BDI was observed at Week 12 for thecombined ambrisentan group, with a placebo-adjusted BDI of −0.6 (95% CI:−1.2 to 0.0; p=0.017). Dose-dependent improvements in BDI were alsoobserved for both the 5 mg and 10 mg dose groups compared to placebo.Due to the multiple comparisons procedure, a statistically significantimprovement compared to placebo could not be stated for this secondaryendpoint.

At Week 12, the geometric mean percent change in plasma ET-1 increasedby 34% (95% CI: 11% to 63%) in the placebo group. The geometric meanpercent change in plasma ET-1 increased from baseline by 96% (95% CI:53% to 151%; p=0.019 versus placebo) in the 5 mg group and by 48% (95%CI: 19% to 84%; p=0.169 versus placebo) in the 10 mg group. The changefrom baseline was substantially greater than placebo for the 5 mg group,but not for the 10 mg group.

At baseline, approximately 90% of plasma cTnT concentrations were belowthe level of quantification (0.01 ng/ml). Changes in cTnT concentrationsduring the 12-week study were minor and not remarkably different fromzero.

At Week 12, the geometric mean percent change in plasma BNP increased by9% (95% CI: −16% to 41%) in the placebo group. In contrast, thegeometric mean percent change in plasma BNP decreased from baseline by30% (95% CI: −43% to −14%; p=0.002 versus placebo) in the 5 mg group andby 45% (95% CI: −57% to −29%; p <0.001 versus placebo) in the 10 mggroup. The decrease from baseline was substantially greater than placebofor the 5 mg group and the 10 mg group.

Efficacy by Subgroup

Improvements in 6MWD were observed for both WHO functional class I/IIand class III/IV subjects at Week 12, however, a slightly greaterimprovement was observed for class III/IV subjects. For the class I/IIsubgroup, the placebo-adjusted 6MWD increase from baseline at Week 12was +25.6 m and +42.0 m for the 5 mg and 10 mg dose groups,respectively. For the class III/IV subgroup, the placebo-adjusted 6MWDincrease from baseline at Week 12 was +34.1 m and +56.9 m for the 5 mgand 10 mg dose groups, respectively.

Improvements in 6MWD at Week 12 were observed in both ambrisentan dosegroups for the idiopathic PAH subgroup and in the 10 mg group for thenon-idiopathic PAH subgroup. There was greater improvement observed insubjects with idiopathic PAH than in subjects with non-idiopathic PAH.For the idiopathic PAH subgroup, the placebo-adjusted 6MWD increasedfrom baseline at Week 12 by +42.9 m and +56.9 m for the 5 mg and 10 mgdose groups, respectively. For the non-idiopathic PAH subgroup, theplacebo-adjusted 6MWD increase from baseline at Week 12 was +10.2 m and+43.0 m, for the 5 mg and 10 mg dose groups, respectively.

Improvements in 6MWD at Week 12 were observed in both ambrisentan dosegroups for female subjects. The placebo-adjusted 6MWD increased frombaseline at Week 12 by +30.9 m and +57.7 m for the 5 mg and 10 mg dosegroups, respectively. For male subjects, the placebo-adjusted 6MWDincrease from baseline at Week 12 was +19.9 m and +13.1 m for the 5 mgand 10 mg dose groups, respectively.

Subjects not receiving calcium channel blockers (CCBs) during the studydemonstrated an improvement in 6MWD at Week 12 compared to placebo afterreceiving ambrisentan, with a placebo-adjusted increase from baseline of+38.7 m and +67.9 m for the 5 mg and 10 mg dose groups, respectively.Subjects receiving CCBs during the study also had an improvement in 6MWDcompared to placebo after receiving ambrisentan, with a placebo-adjustedincrease from baseline of +15.1 m and +19.6 m for the 5 mg and 10 mgdose groups, respectively.

Subjects not receiving supplemental oxygen demonstrated an improvementin 6MWD at Week 12 compared to placebo that was similar to the overallstudy population. Subjects in the placebo group who receivedsupplemental oxygen during the study had a decrease (−25.5 m) frombaseline in mean 6MWD at Week 12; whereas subjects in the 5 mg (+21.1 m)and 10 mg (+48.0 m) groups had notable increases from baseline in mean6MWD.

Safety Results

A summary of adverse events recorded is shown in Table 2.6.

TABLE 2.6 Global summary of adverse events (% of safety population) 5 mg10 mg Combined Placebo ambrisentan ambrisentan ambrisentan Subjects (N =67) (N = 67) (N = 67) (N = 134) with at least 56 (83.5) 56 (83.6) 53(79.1) 109 (81.3) 1 AE with at least 21 (31.3) 34 (50.7) 29 (43.3) 63(47.0) 1 related AE with at least 7 (10.4) 4 (6.0) 7 (10.4) 11 (8.2) 1SAE with an AE 4 (6.0) 2 (3.0) 2 (3.0) 4 (3.0) leading to study dis-continuation who discon- 4 (6.0) 0 (0.0) 2 (3.0) 2 (1.5) tinued thestudy via early escape who died 2 (3.0) 1 (1.5) 1 (1.5) 2 (1.5)

During this 12-week study, 83.5% of the subjects in the placebo groupexperienced at least 1 AE. Similarly, 83.6% of subjects in the 5 mg dosegroup and 79.1% of subjects in the 10 mg dose group experienced at least1 AE during the study.

Overall, more subjects in the placebo group compared to the ambrisentangroups prematurely discontinued from the study due to death, SAEs, AEs,and/or the early escape procedure. A greater percentage of subjects inthe placebo group (6.0%) met the criteria for early escape, compared tosubjects in the combined ambrisentan group (1.5%).

In general, a similar percentage of AEs were assessed as severe in theplacebo and 10 mg groups (19.4% and 17.9%, respectively), whereas alower percentage of AEs were assessed as severe in the 5 mg group(6.0%). A similar percentage of AEs were assessed as moderate in theplacebo and 10 mg groups (38.8% and 37.3%, respectively), whereas ahigher percentage of AEs were assessed as moderate in the 5 mg group(50.7%). The most frequent AE in the combined ambrisentan group wasperipheral edema, and most events were assessed as mild or moderate.

None of the 134 subjects who received ambrisentan developed any elevatedserum aminotransferase concentrations >3×ULN, compared to 2 subjects inthe placebo group. Further, there were no notable mean changes frombaseline at Week 12 for serum ALT and AST, and no differences betweentreatment groups.

The changes in total bilirubin at Week 12 were shown to be substantiallydecreased in the 10 mg and combined ambrisentan groups, compared toplacebo. The changes in alkaline phosphatase at Week 12 were shown to besubstantially decreased in the 5 mg, 10 mg and combined ambrisentangroups, compared to placebo.

Mean decreases in hemoglobin concentration were observed at Week 12 forboth ambrisentan dose groups compared to placebo (placebo, 0.15 g/dl; 5mg, −0.83 g/dl; 10 mg, −0.93 g/dl). The decreases were observed early(Week 4) in the study and did not decrease further with continuedtreatment.

Ambrisentan had no effect on PT, INR or weekly warfarin-typeanticoagulant dose.

Mean uric acid decreased slightly over the 12-week study in the placebogroup (−6.5 μmol/liter); whereas a substantial decrease was observed forthe 5 mg (−21.5 μmol/liter) and 10 mg (−53.3 μmol/liter) groups thatappeared to be dose-dependent.

The analysis of male fertility hormones in combination with a limitednumber of subjects (n=12) providing serial semen samples did not suggestthat ambrisentan was associated with an adverse effect on malereproductive potential.

More specifically, changes over baseline in follicle stimulating hormone(FSH) concentration at Week 12 were small, ranging from +0.52 IU/liter(placebo group) to +1.83 IU/liter (10 mg dose group). Although the FSHconcentrations at Week 12 for the placebo and 5 mg dose groups(8.14±2.49 IU/liter and 9.23±7.21 IU/liter, respectively) suggestpossibility of some spermatogenic dysfunction, the changes observedduring the study were unlikely to be of substantial clinical relevance.

Changes in luteinizing hormone (LH) concentration at Week 12 were small:placebo, −0.07±4.72 IU/liter; 5 mg, −0.15±2.21 IU/liter; 10 mg,+1.28±10.63 IU/liter.

Changes from baseline in mean inhibin B concentration at Week 12 weresimilar across treatment groups: placebo, +13.2±73.55 pg/ml; 5 mg,−4.5±28.00 pg/ml; 10 mg, −7.6±50.97 pg/ml. Based on expert opinion, noneof the mean inhibin B concentrations measured at baseline and Week 12indicated presence or development of spermatogenic dysfunction.

Changes from baseline in testosterone concentration at Week 12 were−2.825±7.20 nmol/l for the placebo group, −0.099±3.48 for the 5 mg dosegroup, and −0.099±3.48 for the 10 mg dose group. Based on expertopinion, these data suggest that ambrisentan did not cause a negativeeffect on testosterone concentration in this study population.

Discussion Example 2

This study demonstrated that both the 5 mg and 10 mg dose of ambrisentanadministered once daily provided statistically significant andclinically relevant improvements in exercise capacity and symptoms insubjects with PAH. The improvements in 6MWD were evident within 4 weeksand appeared dose-dependent by Week 8. At Week 12, the increase in 6MWDwas nearly twice as large in the 10 mg dose group compared to the 5 mgdose group. Improvements in 6MWD were observed in most subgroups and, ingeneral, appeared to be dose-dependent. Clinically relevant improvementsin 6MWD were observed in subjects with WHO functional class I/II andclass III/IV symptoms. Both doses also demonstrated clinically relevanttreatment benefits for several secondary endpoints, including WHOfunctional class and BDI, as well as a notable reduction in plasma BNP.

Ambrisentan was well tolerated as indicated by the lack of dosereduction and AEs leading to premature discontinuation as well as moresubjects in the placebo group discontinued due to death, SAEs, AEs,early escape, right heart failure, and/or worsening PAH. The mostclinically important AEs observed in this study were peripheral edema,headache and nasal congestion. For the most part, these events were mildin severity and none led to study discontinuation. Serumaminotransferase abnormalities, which have been observed andtreatment-limiting for other ERAs, were not observed in any subjectsreceiving ambrisentan. Furthermore, there were no increases in mean ALTand AST and there were notable decreases in mean total bilirubin andalkaline phosphatase in subjects receiving ambrisentan. Decreases inhemoglobin concentration were observed early in the study and did notdecrease further with continued treatment.

In conclusion, the treatment benefits observed for the primary andsecondary endpoints of this study were robust, internally consistent,and clinically relevant. Ambrisentan was well tolerated and wasassociated with a manageable safety profile, indicating a positiverisk-to-benefit profile.

Example 3

The trials described in Examples 1 and 2 enrolled subjects from apopulation having PAH including idiopathic PAH and PAH associated withCTD, anorexigen use or HIV infection. Patients with pulmonaryhypertension due to other etiologies were generally excluded. However,the efficacy and safety of ambrisentan observed in this classic PAHpopulation, and the need for effective therapy in pulmonary hypertensionassociated with other conditions, merits evaluation in thesenon-traditional groups. Therefore, a further study is conducted toevaluate safety and efficacy of ambrisentan in both classic PAH patients(WHO Group 1) and in an expanded pulmonary hypertension patientpopulation (WHO Groups 3 and 4).

This expanded population includes subjects having idiopathic andfamilial PAH; PAH associated with collagen vascular disease, congenitalsystemic-to-pulmonary shunts, HIV infection, drugs and toxins, thyroiddisorders, glycogen storage disease, Gaucher disease and splenectomy;pulmonary hypertension associated with chronic obstructive pulmonarydisease (COPD), interstitial lung disease (ILD), sleep-disorderedbreathing and alveolar hypoventilation disorders; and pulmonaryhypertension due to thromboembolic obstruction of proximal and/or distalpulmonary arteries. Four groups are of particular interest in thisstudy:

-   -   (a) PAH associated with congenital heart defects, including        Eisenmenger's syndrome;    -   (b) PAH associated with HIV infection;    -   (c) pulmonary hypertension associated with ILD; and    -   (d) pulmonary hypertension associated with COPD.

Subjects having pulmonary hypertension associated with ILD or COPD mustdemonstrate a degree of pulmonary hypertension that is disproportionateto the severity of the underlying disease. Subjects with ILD must havetotal lung capacity >60% of predicted normal, mean PAP >35 mmHg, andPVR >3.5 mmHg/I/min (280 dyne.sec/cm⁵). Subjects with COPD must haveforced expiratory volume in 1 second >50% of predicted normal, meanPAP >35 mmHg, and PVR >3.5 mmHg/I/min (280 dyne.sec/cm⁵).

The study is designed to evaluate improvements compared to baseline forthe overall study population and for key subgroups of interest. Thestudy also examines safety and tolerability of ambrisentan in a broadpopulation of subjects with pulmonary hypertension.

The target population includes men and women, 18 years or older, withpulmonary hypertension as defined by the WHO clinical classification.Subjects must have a documented history of pulmonary hypertension and beable to walk at least 150-450 meters in a 6MWT.

Subjects who have discontinued bosentan or sitaxsentan therapy due toaminotransferase abnormalities or lack of efficacy are eligible for thisstudy. Subjects currently receiving chronic prostanoid therapy and/or anoral PDE-5 inhibitor are also eligible for this study.

All subjects must have a documented mean PAP ≧25 mmHg, PVR >3mmHg/1/min, and PCWP or LVEDP <15 mmHg. Subjects with ILD or COPD mustmeet the additional or stricter requirements stated above.

All hemodynamic data represent resting pressures and must be assessed nomore than 1 year (52 weeks) prior to the screening visit. All pulmonaryfunction tests must be assessed no more than 3 months (12 weeks) priorto the screening visit.

Certain etiology subgroups are of particular interest. Therefore, thisstudy enrolls a minimum of 18 subjects in the following etiologysubgroups:

-   -   (a) PAH associated with congenital heart defects, including        Eisenmenger's syndrome;    -   (b) PAH associated with HIV infection;    -   (c) pulmonary hypertension associated with ILD; and    -   (d) pulmonary hypertension associated with COPD.

This study also enrolls a minimum of 30 PAH (WHO Group 1) subjectsreceiving concomitant sildenafil therapy at baseline.

Enrollment continues (up to a maximum of 200 subjects) until theenrollment goals for each of the etiology subgroups, as well as thesildenafil subgroup, have been met.

The primary objective of this study is to evaluate effect of ambrisentanon exercise capacity in a broad population of subjects with pulmonaryhypertension. Secondary objectives are to evaluate effects ofambrisentan on other clinical measures of pulmonary hypertension,long-term treatment success and survival. In addition, safety andtolerability of ambrisentan will be evaluated. Efficacy and safety willbe evaluated in the overall study population and in various subgroups.

Anecdotal evidence suggests that patients with non-classical pulmonaryhypertension may respond more slowly to therapy than the classical PAHpopulation; therefore, the primary analysis of efficacy is evaluatedafter 24 weeks of treatment. Eligible subjects receive 5 mg ambrisentanonce daily for the first 24 weeks. One dose reduction is permittedduring the 24-week fixed-dose treatment period if a subject is nottolerating study drug (e.g., 5 mg to 2.5 mg). After the initial 24-weektreatment period, investigators are allowed to adjust study drug dose asclinically indicated (available doses are 2.5 mg, 5 mg and 10 mg).

Subjects are monitored with clinical laboratory tests every 4 weeksthroughout the study. These safety laboratory tests may be performed ata local phlebotomy laboratory or at the investigator clinic. Inaddition, the investigator assesses each subject for safety and efficacyat Week 4, Week 12 and Week 24. Following Week 24, subjects are assessedfor safety and efficacy every 24 weeks.

Subjects who have received stable sildenafil treatment for at least 4weeks are permitted to enroll in this study and continue receivingsildenafil in combination with ambrisentan. Subjects who are notreceiving sildenafil treatment prior to enrollment are permitted toinitiate concomitant sildenafil treatment; however, prior to addition ofconcomitant sildenafil treatment, investigators must conduct at leastone 6MWT after the subject has received 10 mg q.d. ambrisentan for aminimum of 4 weeks. Up-titration to 10 mg q.d. ambrisentan is allowed atany time after the Week 24 visit; therefore, concomitant sildenafiltreatment may be added after 28 weeks of ambrisentan monotherapy.Furthermore, addition of concomitant sildenafil treatment requires thata subject meet two or more of the following predefined criteria:

-   -   (a) a decrease from baseline of at least 20% in 6MWD;    -   (b) an increase of 1 or more WHO functional class; and/or    -   (c) worsening right ventricular failure (e.g., as indicated by        increased jugular venous pressure, new or worsening        hepatomegaly, ascites or peripheral edema).

The efficacy endpoints of 6MWD, WHO functional class, BDI and BNP mustbe assessed immediately prior to initiation of sildenafil treatment toestablish baseline efficacy prior to combination therapy.

Concomitant administration of an approved prostanoid treatment (i.e.,i.v. epoprostenol, i.v. or subcutaneous treprostinil, or i.v. or inhalediloprost) is permitted at any time after the Week 12 visit. The efficacyendpoints of 6MWD, WHO functional class, BDI and BNP must be assessedimmediately prior to initiation of prostanoid treatment to establishbaseline efficacy prior to combination therapy.

Trough (pre-dose) and peak (2-hour) PK samples are collected at Week 0and Week 4 to assess ambrisentan plasma concentrations. For subjects onconcomitant sildenafil therapy, trough (pre-dose) and peak (1-hour)samples are collected at Week 0 and Week 4 to assess sildenafil andN-desmethylsildenafil plasma concentrations.

Male subjects complete semen and hormone analyses to evaluate potentialeffects of ambrisentan on male fertility.

The primary endpoint of this study is the change from baseline in 6MWDat Week 24 for all subjects.

Secondary endpoints include:

-   -   (a) clinical worsening of pulmonary hypertension, as defined by        time from initiation of ambrisentan treatment to the first        occurrence of death, lung transplantation, hospitalization for        pulmonary hypertension, atrial septostomy, addition of chronic        prostanoid treatment, or study withdrawal due to the addition of        other clinically approved therapeutic agents for pulmonary        hypertension;    -   (b) change from baseline in:        -   (i) WHO functional class;        -   (ii) SF-36® health survey;        -   (iii) BDI immediately following exercise; and/or        -   (iv) BNP;    -   (c) monotherapy treatment status, as defined by time from        initiation of ambrisentan treatment to addition of sildenafil,        iloprost, treprostinil or epoprostenol to ongoing ambrisentan        treatment;    -   (d) failure-free treatment status, as defined by time from        initiation of active treatment to the first occurrence of death,        lung transplantation, or study withdrawal due to addition of        other clinically approved therapeutic agents for pulmonary        hypertension; and    -   (e) long-term survival, as defined by time from initiation of        ambrisentan treatment to death.

Incidence and severity of adverse events associated with ambrisentantreatment, including elevations in AST and ALT >3×ULN, are evaluated forall subjects, as well as for key etiology subgroups, and concomitantsildenafil or prostanoid treatment.

All patents and publications cited herein are incorporated by referenceinto this application in their entirety.

The words “comprise”, “comprises”, and “comprising” are to beinterpreted inclusively rather than exclusively.

What is claimed is:
 1. A method for treating a pulmonary hypertensioncondition in a subject, comprising administering a therapeuticallyeffective amount of ambrisentan to the subject, wherein, at baseline,time from first diagnosis of the condition in the subject is not greaterthan about 2 years.
 2. The method of claim 1, wherein the pulmonaryhypertension condition comprises pulmonary arterial hypertension (PAH).3. The method of claim 2, wherein the PAH comprises idiopathic PAH,familial PAH or PAH associated with another disease or condition.
 4. Themethod of claim 2, wherein the PAH at baseline is of at least WHO ClassII.
 5. The method of claim 1, wherein, at baseline, time from firstdiagnosis of the condition in the subject is not greater than about 0.5years.
 6. The method of claim 1, wherein the subject experiences atleast one of (a) adjustment of one or more hemodynamic parametersindicative of improvement of the pulmonary hypertension conditiontowards a more normal level versus baseline; (b) increase in exercisecapacity versus baseline; (c) lowering of Borg dyspnea index (BDI)versus baseline; (d) improvement of one or more quality of lifeparameters versus baseline; and/or (e) movement to a lower WHOfunctional class.
 7. The method of claim 6, wherein mean pulmonaryarterial pressure (PAP) is lowered by at least about 3 mmHg versusbaseline.
 8. The method of claim 6, wherein mean PAP is lowered by atleast about 5 mmHg versus baseline.
 9. The method of claim 6, whereinexercise capacity is increased as measured by an increase of at leastabout 10 m in 6-minute walking distance (6MWD).
 10. The method of claim6, wherein exercise capacity is increased as measured by an increase ofat least about 20 m in 6MWD.
 11. The method of claim 6, wherein BDI islowered by at least about 0.5 index point versus baseline.
 12. Themethod of claim 6, wherein BDI is lowered by at least about 1 indexpoint versus baseline.
 13. The method of claim 1, wherein theambrisentan is administered orally once a day.
 14. The method of claim13, wherein the ambrisentan is administered in a daily dosage amount ofabout 1 mg to about 25 mg.
 15. The method of claim 13, wherein theambrisentan is administered in a daily dosage amount of about 2.5 mg toabout 10 mg.
 16. The method of claim 1, wherein the ambrisentan isadministered for a treatment period of at least about one month.
 17. Themethod of claim 16, wherein the treatment period is at least about threemonths.
 18. The method of claim 1, wherein the ambrisentan isadministered in monotherapy.
 19. The method of claim 1, wherein theambrisentan is administered in combination therapy with a second activeagent effective for treatment of the pulmonary hypertension condition ora condition related thereto.
 20. The method of claim 19, wherein thesecond active agent comprises at least one drug selected from the groupconsisting of prostanoids, phosphodiesterase-5 (PDE5) inhibitors,endothelin receptor antagonists (ERAs) other than ambrisentan, calciumchannel blockers, diuretics, anticoagulants, oxygen and combinationsthereof.
 21. A method for providing an improved prognosis for a subjecthaving a pulmonary hypertension condition, the method comprisingadministering to the subject ambrisentan at a dose and frequency and fora treatment period effective to provide (a) a reduction in probabilityof a clinical worsening event during the treatment period, and/or (b) areduction from baseline in serum brain natriuretic peptide (BNP)concentration, wherein, at baseline, time from first diagnosis of thecondition in the subject is not greater than about 2 years.
 22. Themethod of claim 21, wherein, at baseline, time from first diagnosis ofthe condition in the subject is not greater than about 0.5 years. 23.The method of claim 21, wherein the dose, frequency and period ofambrisentan administration are effective to provide a reduction of atleast about 25% in probability of a clinical worsening event during thetreatment period.
 24. The method of claim 21, wherein the dose,frequency and period of ambrisentan administration are effective toprovide a reduction of at least about 50% in probability of a clinicalworsening event during the treatment period.
 25. The method of claim 21,wherein the dose, frequency and period of ambrisentan administration areeffective to provide a reduction of at least about 80% in probability ofa clinical worsening event during the treatment period.
 26. The methodof claim 21, wherein the dose, frequency and period of ambrisentanadministration are effective to provide a reduction of at least about50% in probability of death, lung transplantation, hospitalization forpulmonary arterial hypertension, atrial septostomy or an aggregatethereof during the treatment period.
 27. The method of claim 21, whereinthe dose, frequency and period of ambrisentan administration areeffective to provide a reduction from baseline of at least about 15% inBNP concentration.
 28. The method of claim 21, wherein the dose,frequency and period of ambrisentan administration are effective toprovide a reduction from baseline of at least about 25% in BNPconcentration.
 29. The method of claim 21, wherein the dose, frequencyand period of ambrisentan administration are effective to provide areduction from baseline of at least about 50% in BNP concentration. 30.The method of claim 21, wherein the pulmonary hypertension conditioncomprises PAH.
 31. The method of claim 30, wherein the subject hasidiopathic PAH.
 32. The method of claim 30, wherein the subject hasnon-idiopathic PAH.
 33. The method of claim 32, wherein thenon-idiopathic PAH is secondary to scleroderma, systemic lupuserythematosus, anorexigen use or HIV infection.
 34. The method of claim30, wherein the PAH at baseline is of at least WHO Class II.
 35. Themethod of claim 21, wherein the subject at baseline has at least one of(a) mean PAP of at least about 25 mmHg at rest or at least about 30 mmHgwhile exercising, (b) pulmonary vascular resistance (PVR) of at leastabout 3 mmHg/L/min, and/or (c) pulmonary capillary wedge pressure (PCWP)or left ventricle end diastolic pressure (LVEDP) not greater than about15 mmHg.
 36. The method of claim 35, wherein the subject the subject atbaseline has all three of (a) mean PAP of at least about 25 mmHg at restor at least about 30 mmHg while exercising, (b) PVR of at least about 3mmHg/L/min, and (c) PCWP or LVEDP not greater than about 15 mmHg. 37.The method of claim 21, wherein the subject at baseline has mean PAP atrest of at least about 40 mmHg.
 38. The method of claim 21, wherein theambrisentan is administered orally once a day.
 39. The method of claim38, wherein the ambrisentan is administered in a daily dosage amount ofabout 1 mg to about 25 mg.
 40. The method of claim 38, wherein theambrisentan is administered in a daily dosage amount of about 2.5 mg toabout 10 mg.
 41. The method of claim 21, wherein the treatment period isat least about one month.
 42. The method of claim 21, wherein thetreatment period is at least about three months.
 43. The method of claim21, wherein the ambrisentan is administered in monotherapy.
 44. Themethod of claim 21, wherein the ambrisentan is administered incombination therapy with a second active agent effective for treatmentof the pulmonary hypertension condition or a condition related thereto.45. The method of claim 44, wherein the second active agent comprises atleast one drug selected from the group consisting of prostanoids,phosphodiesterase-5 (PDE5) inhibitors, endothelin receptor antagonists(ERAs) other than ambrisentan, calcium channel blockers, diuretics,anticoagulants, oxygen and combinations thereof.
 46. The method of claim21, wherein the dose, frequency and period of ambrisentan administrationare additionally effective to improve pulmonary function of the subjectover baseline as measured by at least one of exercise capacity and/orBDI.
 47. The method of claim 21, wherein the dose, frequency and periodof ambrisentan administration are additionally effective to enhancequality of life of the subject over baseline as measured by an increasein one or more parameters in an SF-36® health survey.
 48. The method ofclaim 47, wherein an increase of at least about 1 point is observed inone or more parameters in the survey.
 49. The method of claim 21,wherein the dose, frequency and period of ambrisentan administration areadditionally effective to maintain or improve WHO functional class. 50.The method of claim 21, wherein the subject is female.
 51. The method ofclaim 21, wherein the subject is male and fertility of the subject isnot substantially compromised.
 52. A method for prolonging life of asubject having a pulmonary hypertension condition, comprisingadministering to the subject ambrisentan at a dose and frequency and fora treatment period effective to increase life expectancy, from a time ofinitiation of treatment, by at least about 30 days, wherein, atbaseline, time from first diagnosis of the condition in the subject isnot greater than about 2 years.
 53. A method for extending time toclinical worsening in a subject having a pulmonary hypertensioncondition, comprising administering to the subject ambrisentan at a doseand frequency and for a treatment period effective to decrease theprobability of a clinical worsening event by at least about 25%,wherein, at baseline, time from first diagnosis of the condition in thesubject is not greater than about 2 years.
 54. A method for treating apulmonary hypertension condition in a reproductively active malesubject, the method comprising administering a therapeutically effectiveamount of ambrisentan to the subject, wherein fertility of the subjectis not substantially compromised.
 55. A method for treating PAH in asubject, comprising administering a therapeutically effective amount ofambrisentan to the subject, wherein the PAH is associated with one ormore of (a) a congenital heart defect, (b) portal hypertension, (c) useof a drug or toxin other than an anorexigen, (d) thyroid disorder, (e)glycogen storage disease, (f) Gaucher disease, (g) hereditaryhemorrhagic telangiectasia, (h) hemoglobinopathy, (i) myeloproliferativedisorder, (j) splenectomy, (k) pulmonary veno-occlusive disease or (l)pulmonary capillary hemangiomatosis.
 56. A method for treating apulmonary hypertension condition classified in WHO Groups 2-5 in asubject, comprising administering a therapeutically effective amount ofambrisentan to the subject.
 57. The method of claim 56, wherein thecondition comprises left-sided atrial or ventricular heart diseaseand/or left-sided valvular heart disease.
 58. The method of claim 56,wherein the condition is associated with one or more of chronicobstructive pulmonary disease (COPD), interstitial lung disease,sleep-disordered breathing, an alveolar hypoventilation disorder,chronic exposure to high altitude, a developmental abnormality,thromboembolic obstruction of proximal and/or distal pulmonary arteries,a non-thrombotic pulmonary embolism, sarcoidosis, histiocytosis X,lymphangiomatosis, and/or compression of pulmonary vessels.